essay about biology and chemistry

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Relationship Between Chemistry and Biology

Chemistry is important to biology. This is why, when you open an introductory biology textbook, early chapters discuss the relationship between chemistry and biology. Understanding atoms , compounds, and chemical reactions is central to how biology works. So, one common homework question is asking students to explain why chemistry is important to biology and give examples of the relationship between the two disciplines.

The Relationship Between Chemistry and Biology

Chemistry is a physical science, like physics. Meanwhile, biology is a life science. You can pick up a physics text and never encounter a biological concept. You can get pretty far into chemistry before you encounter biology, but eventually you’ll study organic chemistry, and biochemistry. A biology book, meanwhile, includes a periodic table and at least a general introduction to atoms, chemical formulas, and reactions. Often, a brief introduction to chemistry is one of the first topics in the study of biology.

This is because biology is the study of life and all living things consists of atoms and molecules. Specifically, life depends on carbon or organic chemistry . Proteins, lipids, carbohydrates, and nucleic acids ( DNA and RNA ) are all organic molecules. Sometimes the relationship between chemistry and biology isn’t immediately obvious. For example, if you look at an ecosystem and identify organisms in a food web, it might not seem like chemistry. But, the resources organisms compete for include nutrients, which are chemicals. Similarly, if you study the anatomy of a human, you don’t initially see the chemistry. You see organs, tissues, and cells. Only when you look more closely do you see neurotransmitters, ions, hormones, lipid bilayers, and other chemistry concepts.

Examples of the Importance of Chemistry in Biology

Here are some examples of the importance of chemistry in biology:

• Photosynthesis is the way plants make food (a molecule called glucose). It’s a set of chemical reactions that feeds not only plants, but also animals and fungi.
• Other processes in plants that rely on chemistry include leaf color change and fruit ripening. Knowing the chemistry of the processes helps explain and predict conditions relating to the seasons and crop production.
• Inheritance and genetics depends on deoxyribonucleic acid or DNA. The genes that code for traits direct cells to make and express proteins. So, you use chemistry when explaining how two tall plants can produce some tall and some short plants or why two people with brown eyes might have blue-eyed children.
• How bones build calcium, why teeth decay if your diet is high in sugar, and why proteins don’t dissolve in saliva are all matters of chemistry.
• Chemistry explains the action of medications, supplements, and toxins.

Do you have additional examples of the relationship between chemistry and biology? Feel free to leave a comment!

• Astbury, W.T. (1961). “Molecular Biology or Ultrastructural Biology?”. Nature . 190 (4781): 1124. doi: 10.1038/1901124a0
• Ben-Menahem, Ari (2009). Historical Encyclopedia of Natural and Mathematical Sciences . Berlin: Springer. ISBN 978-3-540-68831-0.
• Fromm, Herbert J.; Hargrove, Mark (2012). Essentials of Biochemistry . Springer. ISBN 978-3-642-19623-2.
• Fruton, Joseph S. (1999). Proteins, Enzymes, Genes: The Interplay of Chemistry and Biology . New Haven: Yale University Press. ISBN 0-300-07608-8.
• Roberts, Keith; et al. (2002). Molecular Biology of the Cell (4th ed.). Routledge. ISBN 0-8153-3218-1.

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Chemistry Vs. Biology

Table of Contents

Key Takeaways

• Chemistry and biology are popular majors with distinct areas of study.
• Chemistry offers career opportunities in pharmaceuticals, environmental science, and materials science.
• Biology graduates can pursue careers in healthcare, research, and conservation.
• The demand for chemists is projected to grow by 7% with a median annual salary of $78,790, while biologists can expect a 5% increase in employment with a median yearly wage of $82,220.

Overview of the two majors: Chemistry and Biology

Overview of the curriculum and coursework of the two majors.

Overview of coursework, assessments, and laboratory experiments

Comparison of skills developed: critical thinking and problem-solving.

Comparison of Career Opportunities and Job Roles in Chemistry Vs. Biology

Comparison of salary potential: job market trends.

Similarities and differences between the two majors

How are the principles of biology and chemistry applied in forensic science.

In forensic science, biology is used to analyze DNA samples from crime scenes to match with potential suspects. Chemistry plays a crucial role in forensic toxicology, determining the presence of drugs or poisons in the body. The principles of biology and chemistry are applied in forensic science to solve crimes and bring justice.

Difference between the two majors: specializations

Factors to consider when choosing between Chemistry and Biology majors: Interests

• Subject matter : Chemistry focuses on the composition, properties, and reactions of matter, while Biology explores living organisms and their processes.
• Career prospects : Think about the potential career paths each major offers. Chemistry can lead to jobs in pharmaceuticals, materials science, or environmental research, while Biology can open doors in healthcare, genetics, or ecology.
• Laboratory work : Chemistry involves extensive lab work, while Biology may involve fieldwork and hands-on experimentation.
• Course requirements : Examine the required courses in each major to see which aligns better with your strengths and interests.

What is the Difference Between Chemistry and Chemical Biology?

Chemistry focuses on the composition and properties of substances, while chemical biology explores how chemicals interact with living organisms. The main difference between chemical engineering is that chemistry delves into the fundamentals of matter, while chemical biology is concerned with the chemical processes within living systems.

BIOLOGY JUNCTION

Test And Quizzes for Biology, Pre-AP, Or AP Biology For Teachers And Students

How to Write a Biology Essay

“The point of the essay is to change things.” – Edward Tufte

Writing a biology essay can be a complex task, requiring not only a deep understanding of the subject but also the ability to present scientific information clearly and effectively. Prepare well and exploit a structured approach to crafting a compelling and well-researched biology text. Some simple steps go from understanding the assignment and conducting detailed research to structuring your essay and incorporating credible sources so that you can reach academic excellence without any complications. For qualitative preparation check out biology essay examples on a trustworthy source and follow the expert instructions to ensure your text meets the high standards of scientific writing.

Understand the Biological Context

You will hardly create any qualitative content unless you clearly understand what you are going to write about. Identify the biological concept or phenomenon that is to be at the center of your writing. If you have any hesitations or your assignment seems ambiguous to you, consult your professor for clarifications or any educational assistant for further directions.

What can help you dive deeper into your biological context is also a literature review. Proceed through a thorough literature review to understand the current state of research on the topic. Look up databases like PubMed, Google Scholar, and institutional libraries.

Formulate a Hypothesis or Research Question

Pass on to generate a hypothesis or research question that is going to be the core of your essay. If your writing involves an experimental or observational study, formulate a clear, testable hypothesis. Develop a specific research question to guide your investigation if it’s a review or analytical essay. So, define the type of your text and formulate its central point respectively for further successful steps.

Conduct Detailed Research and Data Collection

Now that you know your context and your attitude as for the assignment it is time to back it up with the proof. Start with primary sources, covering research articles, original studies, and scientific experiments. When you have enough, pass on to secondary sources, such as review articles, meta-analyses, and books for broader context.

Additionally, biological research allows you to conduct data analysis to strengthen your essay arguments. If the step is relevant to your work, analyze raw data from experiments or existing datasets using statistical methods. Create or refer to graphs, tables, and figures to present data effectively.

Create and Follow a Structured Outline with Scientific Rigor

Sometimes it is very difficult to organize your work properly so that you can finish it on time and produce qualitative content without any delay. So the very next step is to create a structured outline with scientific rigor so that you can stick to it to write a fundamental essay.

● Abstract – if you are required to, begin with an abstract. Provide a concise summary of the essay, including the research question, methods, key findings, and conclusions.

● Introduction – the next step or the primary point when an abstract is not necessary is to write an introduction. For your introduction include detailed background information with references to key studies and findings. Explain the significance of the topic within the field of biology. And don’t forget to state your thesis or hypothesis clearly. The rest of your writing will be tied to it. Be confident you’ve singled out the central idea of your topic and the findings related.

● Methods – if necessary or stated in the assignment, dwell on the methods you’ve exploited when researching and writing. Provide a description of the experimental design, including controls, variables, and procedures. Add the list of materials and equipment used. Explain how data was collected and recorded. This part of the essay will be solid proof of your no-plagiarism work.

● Results – think of the way you are going to display the results of your research and organize them appropriately. Present data in an organizedmanner using figures, tables, and charts. Add statistical tests if used and their outcomes.

● Discussion – remember that you not only have to present the data and evidence you have collected but also analyze and show your attitude to the findings. Interpret the results in the context of the research question or hypothesis. Compare findings with previous studies and discuss similarities and differences. Be open about any limitations in your study or analysis.

● Conclusion – with the analysis of your findings ready, you should summarize your work with a proper conclusion. Dwell on how your findings support or disprove the thesis/hypothesis. Discuss the broader implications of your findings for the field of biology. Suggest areas for further research.

Make an outline and cover it step by step so that you have a logical and strong text in the end. This will help you to get everything important and finish up your essay on time. Usually with a scientific assignment, you don’t need the inspiration to guide you but should have a proper organization of the writing process to assist you. Outlining will be a crucial part of your well-organized work with the essay.

Incorporate Scientific Evidence

Your biological essay will be no more but the words compound together unless you exploit strong scientific evidence to support your arguments. Ensure all references are from peer-reviewed scientific journals or reputable academic sources. Use a consistent citation style (e.g., APA, MLA, Chicago) and include in-text citations and a bibliography to guarantee the genuineness and trustworthiness of your sources and proofs.

Exploit direct quotations sparingly; prefer paraphrasing and summarizing with proper citations. Put the evidence in between your personal conclusions and attitude to the issue you are addressing in your writing. This will display you have processed the question under study deeply and made your own conclusions out of your findings.

Consider Formatting and Technical Details

Scientific essay requires a relevant approach to its formatting and presentation. Use proper scientific nomenclature, italicizing genus and species names (e.g., Homo sapiens). Make sure you exploit standard units of measurement (SI units) and provide conversions if necessary. Define acronyms and abbreviations the first time they are used. Pay attention to these points when proofreading and editing or get someone to help you with a fresh look. A thorough approach and consistency in details will only add to the quality of your essay.

Spend Time on Proofreading and Peer Review

Take care your scientific essay looks appropriate and proves your level of qualification. Proofreading and thorough review will help you create a desirable image for your writing. Check for grammatical errors, scientific accuracy, and clarity. Use apps and tools to optimize and speed up the process. If possible, have your writing reviewed by a peer or mentor in the field for additional feedback. Or reach out to professionals from online services for high-end proofreading and review.

Care about Adherence to Ethical Guidelines

In the age of tolerance, you should also be confident that your essay doesn’t diminish or offend anyone’s rights and position as to your topic under study. Begin with ethical considerations. If your writing involves discussing experiments on humans or animals, ensure it adheres to ethical guidelines and includes necessary approvals. Additionally, avoid plagiarism by properly citing all sources and using original language. Check your text for authenticity with the help of anti-plagiarism tools on the Internet but beware of scams for anyone to steal your work.

Biology Essay Conclusion

Writing a biology essay involves proper planning, thorough research, and attention to detail. Cover some essential measures so that you can craft a well-structured and scientifically sound text that effectively communicates your findings and arguments. Mind the assignment and formulating a hypothesis to presenting data and discussing implications since each element plays a crucial role in the overall quality of your work. Remember to adhere to ethical guidelines, properly cite all sources, and seek feedback from peers or mentors. With these tools and strategies, you’ll be well-equipped to produce a high-quality biology essay that displays your knowledge and analytical skills.

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Free Biology Essay Examples & Writing Tips

Don’t know what to write about in your essay on biology? Looking for good biology essay examples for inspiration? This article has all you need!

A biology essay is a type of academic paper that focuses on a particular topic of biology. It can discuss animal life, cycles in biology, or a botanic subject. You will need to demonstrate your critical thinking skills and provide relevant evidence to support your perspective.

On this page, you will find examples of biology essays. You will also find here tips and topics prepared by our experts . They can assist you in nailing your short or extended essay.

If you’ve been assigned to write a biology essay, you probably know which area of research you have to choose. However, it might be beneficial to explore other available scopes. It’s useful for both interdisciplinary study and the cases when you are free to pick your area of research. In this section, let’s figure out what you can study in biology.

Here are biological areas of research you should be familiar with:

• Cancer Biology studies this type of disease to prevent, detect, diagnose and cure it. The ultimate goal of such biologists is to eliminate cancer.
• Cell Biology is a branch that studies the structure, function, and behavior of cells. Here, biologists study healthy and sick cells to produce vaccines, medication, etc.
• Biochemistry is an application of chemistry to the study of biological processes on cell and molecular levels. It is a cross-discipline between chemistry and biology. The focus is on the chemical processes of living organisms.
• Computation Biology is a study of biological data that develops algorithms and models to understand biological systems. Here, scientists either work for institutions or research for private enterprises.
• Genetics is an area that focuses on the study of genes and genetic variations for health benefits. It looks at the way DNA affects certain diseases.
• Human Disease is an area within which scientists study different diseases. The field covers cancer, developmental disorders, disease genes, etc.
• Immunology is a branch of biology that focuses on immunity. Immunologists look at the way the body responds to viruses as a way to protect the organism.
• Microbiology studies all living organisms that are too small for our eye to see. It includes bacteria, viruses, fungi, and other microorganisms.
• Neurobiology is the study of the nervous system. Biologists examine the way the brain works and look into brain illnesses.
• Stem Cell and Developmental Biology seeks to examine how the processes behind stem cell’s ability transform cells. The biologists in this area use the power of stem cells to model human illnesses.

Want to know how to start a biology essay? Wondering about the best way to write your essay on biology? Then check out the following tips.

When you’re writing about biology, pay attention to the following features:

• Introduction . Just as in any other form of academic writing, the first section of your paper introduces the subject. Here, explain why your ideas are relevant to biology as a science.
• Thesis Statement. The final one or two sentences of the first paragraph should include your original hypothesis and experiment. You will be proving them in the main body. You do not have to include the results as the reader will encounter them later. If you’re struggling with this part, try our thesis generator .
• Main Body. In this part, write about all the experiments in detail. Often, teachers require to include visual aid to prove your point. For Zoology, Anatomy, Botany, it is pretty easy to find some photos and illustrations.
• Conclusion. Here, restate your thesis. Reemphasize the most critical aspects described in the main body. You can do it by using our summarizing tool . The goal of this last paragraph is to leave an everlasting impression on the reader.

Thank you for reading our article. We hope you found it helpful. Share it with your class peers who also study biology. Additionally, have a look at the biological essay examples below.

746 Best Essay Examples on Biology

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Understanding the Effects of Quantity of Light on Plants Growth

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Nanobiotechnology, Its Advantages and Disadvantages

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Life in the Bottom of the Ocean and Its Protection

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Energy Balance and Expenditure

Practical report: determination of a bacteriophage titer, digestive journey of cheeseburger, computational biology as an essential research area, microbial growth and effect of ph on it.

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Chlamydia Sexually Transmitted Disease

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The elements of biochemistry, atomic structure and bonding, functional groups in biochemistry, why do chemical reactions happen, acids and bases, reactions in organic chemistry, concluding remarks, competing interests, further reading, advanced level texts, essential chemistry for biochemists.

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Amanda L. Jonsson , Mark A.J. Roberts , J.L. Kiappes , Kathryn A. Scott; Essential chemistry for biochemists. Essays Biochem 31 October 2017; 61 (4): 401–427. doi: https://doi.org/10.1042/EBC20160094

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Within every living organism, countless reactions occur every second. These reactions typically occur more rapidly and with greater efficiency than would be possible under the same conditions in the chemical laboratory, and while using only the subset of elements that are readily available in nature. Despite these apparent differences between life and the laboratory, biological reactions are governed by the same rules as any other chemical reaction. Thus, a firm understanding of the fundamentals of chemistry is invaluable in biochemistry. There are entire textbooks devoted to the application of chemical principles in biological systems and so it is not possible to cover all of the relevant topics in depth in this short article. The aim is instead to provide a brief overview of those areas in chemistry that are most relevant to biochemistry. We summarize the basic principles, give examples of how these principles are applied in biological systems and suggest further reading on individual topics.

Biochemical systems carry out an enormous variety of chemical reactions with great efficiency. These reactions can be catabolic, breaking down larger molecules to release energy and to generate precursors for further reactions, and/or anabolic, combining molecules together to generate biologically useful molecules. When a chemist carries out a reaction in the laboratory, they have numerous different techniques that can be applied to increase the yield or rate of a reaction; they can alter the temperature or pressure or perhaps add a catalyst. In contrast, biological systems have to carry out the reaction at the temperature maintained by the organism, and, with the exception of organisms living deep in the ocean, at atmospheric pressure. In biological systems, enzymes are employed to increase the rate of reaction; enzymes are proteins whose substrate-binding site acts to lower the energy of high energy species along the reaction pathway from starting material to product. They can achieve enormous enhancement in the rate of reaction compared with the uncatalysed reaction. The classic example is the enzyme triose phosphate isomerase which interconverts dihydroxyacetone phosphate and d- glyceraldehyde-3-phosphate during the breakdown of glucose. This reaction occurs 10 9 times faster in the presence of the enzyme than when uncatalysed [ 1 ].

These rate enhancements are particularly remarkable when we consider that less than a third of the naturally occurring elements are used by biological systems. In order to be exploited in a biological system, elements must be sufficiently abundant in a form that can be taken up by living things. Thus, many catalytic species that are in common use in the laboratory are simply not available for biochemical reactions, for example palladium, used in the addition of hydrogen across a double bond. Of the elements in the periodic table, 28 are essential for animal life ( Figure 1 ); the most recent element found to be essential is bromine, which was found to be required for the proper formation of networks by the protein collagen IV in 2014 [ 2 ]. Of the 28 essential elements, 11 make up 99.9% of the atoms in the human body. The other 17 are known as trace elements and are present in very small amounts, ranging from a milligram to gram quantities in an adult human.

Periodic table illustrating the elements essential for life

The 28 elements essential for animal life are indicated by coloured squares; trace elements are shown in yellow and those present in larger quantities are shown in green. The six most abundant elements in the human body are carbon, hydrogen, oxygen, nitrogen, phosphorus and calcium, accounting for almost 99% of the mass of an adult human. Carbon, hydrogen, oxygen and nitrogen are the building blocks of organic biomolecules, calcium is present in large amounts in bones and teeth (in addition to being vital for cell signalling in smaller amounts), phosphorus is likewise found in bones and teeth (smaller quantities are a vital part of DNA, adenoside triphosphate – the energy currency of the cell – and play an important role in cell signalling).

Electrons in atoms are organized into a series of shells with successively higher energies (and greater distance from the nucleus). The shells are identified by the principal quantum number which takes integer values from one to seven for the elements of the current periodic table. The shell with principle quantum number 1 has the lowest energy with 2 being the next highest in energy, and so on. Within a shell there are subshells designated by the letters s, p, d and f, and within each subshell electrons occupy orbitals: regions of space that may be occupied by up to two electrons, and whose energy and shape can be described mathematically by an equation known as the wave function. It is important not to confuse orbitals with an orbit; electrons do not move around the nucleus along a fixed path as they would in an orbit. Instead the wave function allows us to calculate the probability of finding an electron at a particular position around the nucleus. Different subshells have different numbers of orbitals; s subshells have just one orbital and can therefore accommodate only two electrons, p subshells have three orbitals which can be filled by six electrons in total, and d subshells have five orbitals accommodating up to ten electrons. Shells are filled according to the Aufbau principle, i.e. filling the shell with the lowest principal quantum number first.

Arrangements of electrons or electron configurations , in which the outer shell (the occupied shell with highest principle quantum number) is full are more favourable than those in which it is partially filled. Of the elements in the periodic table, only the noble gases in group 18 have full outer shells. Bond formation, the movement of electrons between atoms, allows other elements to achieve this configuration. Chemical bonds can be covalent, where electrons are shared between atoms or ionic, where electrons are transferred from one atom to another resulting in one positively and one negatively charged species. Looking at the number of electrons in the outer or valence shell enables us to work out how many bonds an atom would need to form in order to fill its outer shell. It is important to note, however, that a bond will only actually form if the energy of the electrons in the bond is lower than the energy of those electrons in the isolated atoms.

As the majority of biological chemistry relates to covalently bonded molecules composed primarily of the elements carbon, hydrogen, nitrogen and oxygen, it is particularly important to know how many bonds each of these elements form. Hydrogen, with its single valence electron requires one additional electron to achieve the noble gas configuration and therefore makes only one bond. H + ions (often just called protons), in which the hydrogen atom has lost an electron, also play many roles in biological systems – for example the formation of ATP is driven by a concentration gradient of H + ions across a membrane. Carbon, with four valence electrons, achieves a full outer shell by forming four covalent bonds, for example by sharing an electron with each of four other atoms. Nitrogen has five valence electrons and forms three covalent bonds leaving one pair of non-bonded electrons; a lone pair. The lone pair is important for the reactivity of nitrogen as it can be used to make a new bond with electron-poor species in chemical reactions. The lone pair can also be shared with an H + ion leading to the formation of ammonium, i.e. the lone pair allows nitrogen to act as a base. Finally, oxygen with six electrons makes two covalent bonds and has two lone pairs of electrons. As with nitrogen, the presence of lone pairs on oxygen makes this atom reactive towards electron-poor species, including H + . Although we often refer to H + ions as though they exist in that form, in water free H + forms the hydronium ion H 3 O + very rapidly.

When an ionic bond is formed, electrons are transferred completely from one atom to the other. The interaction in an ionic bond is entirely Coulombic in nature (i.e. only due to the force of attraction between positive and negative particles) and there is no directionality to the interaction. Such a bond occurs when the elements differ widely in their ability to attract electrons or more formally, when there is a very large energy difference between the valence orbitals (the outermost orbitals containing the electrons available to participate in bonding) in the two atoms. Covalent bonding involves sharing of electrons between atoms and occurs when the two atoms are more similar in their ability to attract electrons; i.e. when the valence orbitals have similar energy. Sharing of electrons in a covalent bond requires atomic orbitals on each of the atoms to interact with each other. One of the consequences of this is that, in contrast with ionic bonds, covalent bonds are directional: a new bond cannot form in a region of space where the orbitals that interact to form the new bond have no electron density. Two classes of covalent bonds occur commonly in biological chemistry, σ bonds and π bonds ( Figure 2 A,B). Although a pair of electrons are shared when a covalent bond is formed, however, this sharing is not necessarily equal. Atoms with a strong ability to attract electrons, i.e. low energy valence orbitals, are referred to as electronegative. If the two atoms forming a covalent bond differ in electronegativity then there will be greater electron density closer to the more electronegative atom. This results in a permanent dipole, with one atom partially negatively charged and the other partially positively charged ( Figure 2 C).

σ and π bonds

In these images, atomic orbitals and bonds are depicted as line drawings indicating shape and as isosurfaces, regions of space enclosing a defined fraction of the electron density. ( A ) When two s-orbitals overlap, a σ-bond is formed. In σ bonds, the atomic orbitals overlap ‘head on’ and there is electron density between the two nuclei in the bond. As a result, these bonds are typically strong compared with π bonds between the same elements. ( B ) In a π bond, two p-orbitals overlap laterally, and the nuclei lie in a plane in which there is no electron density. There is less overlapping between orbitals in a π bond than in a σ bond and so these bonds are typically weaker. It should be noted that a double bond, consisting of a σ and π bond is stronger than a single bond between the same two elements as the strength of both the σ and π components are included in the bond strength. ( C ) When a bond is formed between carbon and oxygen, there will be more electron density located near the oxygen atom, as illustrated here in the isosurface for a carbon–oxygen π bond.

Delocalization of electrons

The description of covalent bonding has so far assumed that a covalent bond involves the sharing of one pair of electrons between two atoms, i.e. that the bond is localized. For the majority of biological molecules this description is adequate, however in some cases this description of bonding does not explain the observed properties of a molecule.

A well-known example is benzene. It was originally thought that benzene contained three alternating single and double bonds, however measurements showed that the bonds were all of equal length. We now consider the bonding in benzene not as three pairs of p-orbitals each interacting to make one double bond, but six p-orbitals each interacting with its neighbours to create a ring of electron density above and below the plane of the carbon atoms ( Figure 3 A). Compounds with delocalized rings of electrons are of major importance in biological systems. For example, the bases in DNA all contain delocalized rings as a part of their structures and favourable interactions between the electrons in these rings (referred to as π–π stacking) contribute to the stability of the DNA double helix ( Figure 3 B).

Delocalized structures

( A ) Each of the six carbon atoms in benzene contribute a p-orbital to the delocalized system. A circle in the centre of the ring can be used to highlight the fact that the system is delocalized, however many biochemists prefer to use the alternating bond representation. ( B ) The four bases found in DNA, all have delocalized rings of p-orbitals; in this diagram atoms shown in red each contribute a p-orbital to the delocalized system. It is not immediately obvious that the atoms indicated with an arrow can contribute a p-orbital, however using a more sophisticated approach to bonding we can show that this is the case. Adenine and guanine each have ten electrons in a delocalized ring, while cytosine and thymine have six. ( C ) Representation of the delocalized carboxylate anion. In this system, four electrons two from the double bond and two from the negatively charged oxygen are delocalized over three atoms. ( D ) Retinal has a linear delocalized system including 12 p-orbitals. Each of the atoms that contributes a p-orbital to the delocalized system is shown in red.

Delocalization of electrons does not only occur in rings; another type of system where delocalization occurs is where three (or more) parallel p-orbitals are adjacent. Consider the carboxylate anion (discussed in The carbonyl functional group section) where a carbon atom makes a double bond with one oxygen atom and a single bond with a negatively charged oxygen atom. In this structure, we can visualize the negative charge on the oxygen being used to make a new double bond with the carbon atom and the existing double bond breaking to leave a negative charge on the oxygen atom ( Figure 3 C). Although we can visualize single and double bonds exchanging position within the molecule, this is not an accurate description of bonding in the molecule. In reality, the electron density is spread over three p-orbitals, and a higher electron density exists on the two oxygen atoms than on the central carbon atom. Delocalization of electron density across three p-orbitals is also important in explaining why the bond formed between two amino acids in a protein chain is planar (see Functional groups found in amino acids section). Molecules with electrons are delocalized over a larger number of adjacent parallel p-orbitals are also common in biology. These molecules are usually referred to as conjugated and can be identified by their alternating chain of single and double bonds. For example, retinal, the light-absorbing molecule that is bound to the protein opsin in the photoreceptor cells responsible for vision in mammals, has electron density delocalized across 12 p-orbitals ( Figure 3 D). The long delocalized system is essential for the absorption of light in the visible region of the electromagnetic spectrum.

Non-covalent interactions

Non-covalent interactions, such as the π–π stacking mentioned in the above section, arise due to electrostatic interactions between two different molecules or within the same molecule between atoms that are not bonded together, without the sharing of electrons via a covalent bond. These interactions are much weaker than the covalent bond but they occur very frequently and, as a result, can have a huge influence on the properties of a molecule. Many biomolecules are macromolecules with thousands of atoms and therefore make many hundreds of thousands of non-covalent interactions. Non-covalent interactions are particularly important in proteins. Proteins are polymers of amino acids, synthesized in a linear chain on the ribosome. Each protein chain folds into a specific 3D structure that is essential for its function; non-covalent interactions between the constituent amino acids determine the 3D structure. Non-covalent interactions are also important in DNA where they help to ensure that the sequence of DNA is preserved upon replication; in the lipid bilayer where non-covalent interactions between lipids create a barrier around the cell; and in molecular recognition (discussed in more detail in [ 3 ]). There are several classes of non-covalent interactions; here we discuss van der Waals interactions, hydrogen bonds and briefly, ionic interactions. We also discuss the ‘hydrophobic effect’ which is commonly invoked to explain why non-polar molecules do not disperse in water and why proteins fold.

van der Waals interactions

A dipole is an uneven distribution of electron density within a molecule such that one region of the molecule has a higher electron density than the other and the two regions are equally but oppositely charged. van der Waals interactions occur when a dipole on one molecule interacts with the dipole on another molecule. These dipoles can be permanent or instantaneous. Permanent dipoles occur due to the uneven charge distribution in a covalent bond between two elements that differ greatly in electronegativity. The partially positively charged (δ + ) atom on one molecule can interact favourably with the partially negatively charged (δ – ) atom on another. Interactions between instantaneous dipoles are called London dispersion forces. They are the weakest among the non-covalent interactions, but also the most prevalent. London dispersion forces occur because the electron density in an atom or molecule does not have an even distribution; at any one time the electron density may be higher in one region than the other. The electron density is redistributed with time, thus the regions of high electron density are different from one moment to the next. The uneven charge distribution is called instantaneous dipole . The distribution of the electron density in neighbouring molecules is influenced by the dipole of the first molecule; areas of relative high electron density on one molecule induce an area of low electron density on the neighbouring molecule and vice versa; thus neighbouring molecules form instantaneous dipoles that attract each other. Typically, each of these interactions has a strength of only ∼2 kJ mol −1 (compared with covalent bonds which typically have a strength of hundreds of kJ mol −1 ) and the magnitude of the interaction is strongly distance dependent, approaching zero at a separation of ∼8–10 Å. When molecules have large surface areas that can come into close contact, for example in biological macromolecules, these interactions can make a huge contribution to the total free energy.

Hydrogen bonding

Hydrogen bonds are a special case of dipole–dipole interaction, but are considered separately here as they are vital for the function of many biochemical systems. A covalent bond between hydrogen and an electronegative atom, such as oxygen, nitrogen or fluorine, is polar, with electron density in the vicinity of the hydrogen much lower than that around its bonding partner. The favourable interaction between the δ + hydrogen of one X–H bond (where X is an electronegative element) and the δ – X atom of another is called as a hydrogen bond. Hydrogen bonds are stronger than van der Waals interactions, but weaker than covalent bonds, with a typical strength between 5 and 40 kJ mol −1 . It is important to note that the strength of a hydrogen bond depends heavily on the geometry of the atoms involved; the bonds are strongest when the three atoms involved in the bond are collinear. Hydrogen bonds are responsible for the specificity of base pairing, A to T and C to G, in DNA strands. They also play a key role in formation of structural elements during protein folding.

Ionic interactions

Ionic interactions occur between species that have full, permanent charges, i.e. ions. These interactions are much stronger than hydrogen bonds and London dispersion forces, but are much less common in biological systems. Ionic interactions between oppositely charged amino acids play an important role in stabilizing protein structure, as demonstrated by changes in protein shape with pH. Proteins have evolved to form the correct 3D structure at the pH of the environment where they function. At pH values far above and below the physiological range the charges of some of the amino acids forming the protein are changed (see section on pH and pK a for details). This changes the ionic interactions within the protein, in many cases causing the protein to unfold. Ionic interactions are particularly important in stabilizing proteins found in thermophilic organisms – those that thrive at temperatures above 40°C. Ionic interactions also play a key role in the binding of charged molecules such as ATP to their macromolecular partners.

The ‘hydrophobic effect’

The ‘hydrophobic effect’ is not a separate class of non-covalent interaction, but it is discussed here as the factors that give rise to this effect are very important for structure formation by biological macromolecules and especially proteins. Many molecules or parts of molecules, are hydrophobic or ‘water-hating’ and tend to cluster together when placed in water; this behaviour is often referred to as the hydrophobic effect. The hydrophobic effect is thought to be primarily entropic (see Why do chemical reactions happen? section), arising due to changes in hydrogen bonding within water in the presence of a non-polar molecule. Water forms an extensive network of transient hydrogen bonds which are broken and formed as the water molecules move. If a non-polar species is placed in water, it disrupts the hydrogen bonding networks. To minimize the number of hydrogen bonds lost due to this disruption water forms an ordered shell around the non-polar species. To make a large number of these ordered shells is entropically very unfavourable; clustering non-polar molecules together minimizes the non-polar surface area exposed to water and hence also minimizes the number of ordered water molecules ( Figure 4 ). This is believed to be the primary driving force for burying non-polar groups on the inside of globular proteins and arranging polar groups on the outside. It is also the driving force for the self-assembly of lipid bilayers (discussed in detail in [ 4 ]).

The hydrophobic effect

Water molecules form an ordered structure around a hydrophobic molecule (shown in grey). When two hydrophobic molecules aggregate the surface area exposed to water is reduced; this reduces the number of ordered water molecules in the hydration shell. Having more water molecules disordered in solution is entropically favourable.

The chemical reactivity of an organic compound depends upon the way in which its atoms are bonded together. Certain collections of atoms having the same connectivity occur frequently in organic compounds and these collections are called functional groups. Functional groups have a characteristic chemical behaviour, and it is possible to predict some of the properties of a molecule based on which functional groups are present. When discussing organic compounds we will use the skeletal representation; those unfamiliar with this representation should refer to Figure 5 . Functional groups that are commonly found in biological molecules are shown in Figure 6 .

Displaying molecules using a skeletal representation

The skeletal representation makes use of the fact that carbon and hydrogen are the most common elements in organic compounds, and also that carbon almost always forms four covalent bonds. ( A ) The process of converting a displayed formula into a skeletal formula has three stages: (i) the molecule is drawn with the carbon chain ‘staggered’ in a zigzag; this is important to allow correct identification of the number of carbon atoms in the final molecule and is a better representation of the actual bond angles. (ii) The ‘C’ label for carbon atoms is omitted. (iii) The ‘H’ label for hydrogen atoms is omitted only for hydrogen atoms bonded to carbon. When interpreting a skeletal formula, we assume that carbon will make four bonds; if a carbon appears to make fewer than four bonds in the skeletal representation, then the ‘missing’ bonds are assumed to be to hydrogen atoms. Using the skeletal representation highlights the heteroatoms present in the molecule and becomes particularly useful once we consider how to display different isomers. ( B ) The guidelines for drawing skeletal structures are relatively flexible and in some cases, for example where we wish to draw attention to a particular group of atoms, the ‘C’ symbol for some of the carbon atoms may be shown. It is important not to omit any hydrogen atoms bonded to carbon atoms that are explicitly displayed in this way. ( C ) Wedge and hashed bonds can be used to illustrate the direction of bond vectors relative to the plane of the page.

Functional groups

( A ) This figure illustrates the some of the functional groups that occur frequently in biological systems. In these structures, the wavy bonds represent connections to the rest of the molecule. *In both amine and amide, one or both of the hydrogen atoms bonded to the nitrogen may be replaced by a carbon atom. ( B ) Many biological molecules include a large number of different functional groups, as illustrated by the structure of coenzyme A with the functional groups labelled in blue and red.

Hydrocarbon functional groups

Functional groups containing only carbon and hydrogen may be saturated (containing only carbon–carbon single bonds) or unsaturated (containing one or more carbon–carbon double or triple bonds). Alkanes are saturated molecules and are chemically unreactive compared with other functional groups. Alkanes are non-polar and hydrophobic, interacting less favourably with water than with other non-polar molecules. Alkenes are unsaturated hydrocarbons and they are also hydrophobic. They are, however, more reactive than alkanes, in particular towards the addition of atoms across the double bond. Alkanes and alkenes are abundant in cell membranes, where their hydrophobic nature is important in creating a barrier around the cell that is impermeable to molecules including water, ions and other polar molecules.

Functional groups in which carbon forms a single bond with an electronegative atom

The alcohol, ether, amine and thiol (–SH) functional groups all contain a carbon atom forming a single bond with an electronegative heteroatom (any atom that is not carbon or hydrogen). The difference in electronegativity between the carbon and the heteroatom makes these bonds polar; there is a higher probability of finding the electrons in the bond close to the electronegative atom than to the carbon atom. To indicate this polarization, we often show carbon with a partial positive charge and the electronegative atom with a partial negative charge. This uneven charge distribution greatly influences the reactivity of these molecules, with the carbon atom potentially being reactive towards electron-rich species known as nucleophiles. The electronegative atoms themselves may also be reactive. Oxygen, nitrogen and sulphur all have lone pairs of electrons that can form new covalent bonds in a chemical reaction; amines in particular are reactive towards protons, forming –NH 3 + at physiological pH (see pH and pK a section). The uneven charge distribution also influences the way these molecules interact with water; these functional groups form favourable van der Waals dipole–dipole interactions with water molecules, as described earlier, and their presence will increase the solubility of a compound.

The carbonyl functional group

The carbonyl group, a carbon atom forming a double bond with an oxygen atom, is a part of many different functional groups. Carbonyl groups are found in a vast range of biological molecules, including proteins, DNA and sugars and they take part in many biological reactions. The reactivity of the carbonyl group varies depending upon which other atoms are bonded to the carbonyl carbon. The simplest carbonyl compounds are aldehydes, which have at least one hydrogen atom bonded to the carbonyl carbon, and ketones in which the carbonyl carbon is bonded to two other carbon atoms. As is the case with alcohols, the carbon–oxygen double bond in carbonyl groups is polarized, with the carbon atom partially positively charged and the oxygen atom partially negatively charged. The carbonyl carbon is particularly susceptible to attack by nucleophiles and this makes the carbonyl group useful for the formation of new carbon–carbon bonds. One important example where carbonyl chemistry plays a key role is the formation of the ketone bodies (acetoacetate, β-hydroxybutyrate and the breakdown product acetone). Ketone bodies are water-soluble species that can act as an alternative energy source to glucose in some tissues when glucose is scarce, for example during starvation or intense exercise. The ketone bodies are formed in the liver and then released into the bloodstream for use as a fuel in the heart, brain and muscle.

Carboxylic acids, esters, amides and acyl phosphates are known as carbonyl derivatives. As the name suggests, carboxylic acid functional groups readily lose a proton (the proton bonded to the oxygen atom); the resulting species is referred to as a carboxylate group or carboxylate anion. In these functional groups, the carbonyl carbon forms an additional single bond with an electronegative element. Although at first glance, it might seem as though this should make these carbonyl compounds more susceptible to nucleophilic attack than aldehydes or ketones (because the carbonyl carbon is bonded to more electronegative atoms) this is not actually the case due to delocalization of electrons within the functional group, as described earlier (see section: Delocalization of electrons ). In biological chemistry, reactions involving the interconversion of carbonyl derivatives are very common, for example in protein synthesis where carboxylic acid groups are converted into amides.

Other functional groups

The phosphoanhydride and disulphide groups are much more common in biochemical systems than in the organic chemistry laboratory. Phosphoanhydride groups are found between phosphate groups in ATP, and attack on this functional group by water or other electron-rich species is important in driving chemical reactions forward in the cell. Disulphide linkages can be formed from two thiol groups under reducing conditions. They play an important role in the function of the cellular antioxidant glutathione and also in stabilizing the structure of extracellular proteins.

Functional groups found in amino acids

Amino acids are named for the two functional groups present in their shared molecular backbone, the amine and carboxylic acid groups. Amino acids are the building blocks of proteins/polypeptides with an amide functional group being formed from the amine and carboxylic acid groups during protein synthesis. By convention, the groups that occur in all amino acids are called the ‘main chain’ or ‘backbone’, while those that differ between amino acids are called the ‘side chains’ or ‘R group’ ( Figure 7 ). Twenty amino acids commonly occur in natural proteins. These are shown in Figure 8 , along with the corresponding one-letter codes that are used as an abbreviation when describing the order in which amino acids appear in a protein. Amino acid side chains include a wide variety of different functional groups, from alkanes in alanine, valine, isoleucine and leucine, to the imidazole group in histidine and guanidine group in arginine. The polypeptide chain of a protein folds up into a specific 3D structure, determined by the order in which the amino acids are added to the chain. It can be useful to categorize amino acids according to the chemical properties of their side chains since these determine the role that a particular type of amino acid most commonly plays in protein structure and function. Here, we have classified side chains as non-polar, polar but uncharged, acidic and basic, but it is important to note that several amino acids could be placed in more than one category. In general, amino acids with non-polar side chains are predominantly found in the interior of a protein. Two key exceptions are glycine and proline. Although both lack polar atoms in their side chains, the unusual ring structure of proline and the small size of glycine make them particularly useful in forming loops and so they are often found on the protein surface. The polar side chains make hydrogen bonds either with water or with other polar amino acids and are commonly found on the surface of a protein or buried as a part of an enzyme active site. The polar side chains with alcohol functional groups (serine, threonine and tyrosine) play a particularly important role on the surface of many proteins involved in cell signalling, where they can be modified by the addition of a phosphate group. The addition of the phosphate group changes the chemical nature of the protein surface from polar to charged and therefore alters the interaction with partner proteins. The amino acid cysteine is important in stabilizing the structure of many extracellular proteins through formation of a disulphide bond, two cysteine side chains linked together through their sulphur atoms ( Figure 6 ). The acidic side chains lose a proton to become negatively charged at physiological pH, while the basic side chains gain a proton to become positively charged (see section pH and pK a for more details). Charged side chains are often found at the surface of proteins in pairs with oppositely charged side chains where the resulting ionic interaction helps to stabilize the protein structure.

Amide bonds in a polypeptide

In this figure, the symbol R is used to denote the different functional groups that distinguish the amino acids. The amino acids that polymerize to form a polypeptide or protein are joined together through amide bonds. This bond is often referred to as a peptide bond. The carbon, oxygen and nitrogen atoms of the amide group all lie in the same plane with the lone pair on the nitrogen forming a delocalized system with the electrons from the carbon–oxygen double bond, as was described for the carboxylate anion. The planarity of this bond has important implications for protein structure.

Amino acids

The twenty amino acids commonly found in proteins. Functional groups not illustrated elsewhere are labelled in red. Full names and one-letter codes are given. Amino acids are categorized as non-polar, uncharged polar, acidic and basic according to the composition of their side chains. Methionine and tryptophan are classified as non-polar, despite including the polar atoms sulphur and nitrogen respectively, as both are typically found in the interior of a protein. The sulphur atom in methionine does not participate in hydrogen bonds or act as a nucleophile in enzymatic reactions. In tryptophan, the nitrogen lone pair is delocalized through the indole ring, ensuring that it is likewise unavailable as a nucleophile. Side chains which frequently form hydrogen bonds are classified as polar, those that lose a proton at physiological pH are acidic, and those that gain a proton are basic. Histidine could be considered both polar uncharged and basic as it exists in both neutral and positively charged state at physiological pH.

Isomers have the same molecular formula, but differ in structure. Isomers are classified according to whether they differ in atom connectivity or in 3D shape.

Structural isomerism

Structural isomers occur when the atoms are bonded together in a different order. Structural isomers are classified into three groups: chain isomers, position isomers and functional group isomers. Chain isomers have the same functional groups bonded to different carbon frameworks. Position isomers have the same carbon framework and type of functional groups but differ in the position of those functional groups. Functional group isomers contain different functional groups (and hence typically have different carbon frameworks) ( Figure 9 A).

Structural isomers and cis-trans isomers

( A ) This figure illustrates the three classes of structural isomers: chain isomers, position isomers and functional group isomers. ( B ) The fatty acid oleic acid has a cis -double bond and is often incorporated into the lipids forming the cell membrane. In contrast, elaidic acid which has a trans -double bond is not found in cell membranes. ( C ) 11- cis -retinal is converted into all- trans -retinal on absorption of light of the appropriate energy in the first step of light detection in the eye.

Stereoisomerism

In biochemistry, a more subtle kind of isomerism, stereoisomerism, is vitally important. Here the connectivity of the atoms in the isomers is identical, but the spatial arrangement of the atoms differs. The two classes of stereoisomers we will consider here are cis-trans isomers and molecules with chiral centres.

Cis-trans isomerism

Cis-trans isomerism, sometimes known as geometrical isomerism, occurs in molecules with double bonds and arises because there is no rotation of groups about a double bond. In the cis -isomer, the extending carbon chains are on the same side of double bond, while in the trans -isomer they are on opposite sides of the bond. The two different isomers have different physical and chemical properties; for example melting points often differ considerably between the cis and trans isomers.

Having the correct cis or trans isomer of a molecule can be vital for biological function, for example in the lipid membrane surrounding cells. Lipids have a hydrophilic head-group bonded to long hydrocarbon ‘tails’. These lipids self-assemble into lipid bilayers in which the hydrophilic head-groups form the outer and inner surfaces of the bilayer and the hydrocarbon tails form the interior of the bilayer. It is important for cellular function that the lipid bilayer surrounding the cell incorporates lipids whose fatty acid tails have the correct stereochemistry. The two fatty acids shown in Figure 9 B, oleic acid and elaidic acid, differ only in the configuration of the double bond, however, only oleic acid is found in cell membranes. The physical properties of a cell membrane are dependent on how well the lipid tails pack together. If the tails pack together very tightly, as in a bilayer containing only saturated fatty acids, then the membrane becomes rigid and does not function properly. Incorporation of fatty acids with cis- double bonds creates disorder among the lipid tails which leads to a more flexible cell membrane. Organisms that are adapted to low temperature have a higher proportion of unsaturated cis- fatty acids than those living at moderate temperatures; this helps to prevent the lipid freezing at low temperatures (for more details, see [ 4 ]).

In some systems, it is the interconversion between cis and trans isomers that is important for biological function. This is the case for retinal in the opsin proteins of photoreceptor cells ( Figure 9 C). In the ground state, retinal adopts the 11- cis configuration. On absorption of a photon of light in the visible range, isomerization to all- trans -retinal takes place. The changes in the shape of retinal due to isomerization trigger changes in the 3D structure of the opsin protein, ultimately leading to a nerve impulse to the brain where the visual signal is interpreted.

Optical isomerism and chirality

A carbon atom bonded to four different substituents is called an asymmetric carbon atom or chiral centre, as there is no centre or plane of symmetry associated with it. There are two possible spatial arrangements for the four substituents around the central carbon; these two arrangements are mirror images. If there is just one asymmetric carbon atom in a molecule, then there are two possible stereoisomers, known as enantiomers. The physical properties of the enantiomers are identical except that they rotate plane polarized light in opposite directions; for this reason enantiomers are sometimes called optical isomers. The enantiomer that rotates polarized light clockwise is designated (+) and that which rotates polarized light anticlockwise is designated (–).

The ability to rotate plane polarized light is a property of the whole molecule and we cannot predict from knowledge of the structure how the plane of polarized light will rotate. Consequently, a more systematic nomenclature is desirable. Organic chemists use the Cahn–Ingold–Prelog rules to assign asymmetric carbon atoms as either ‘ R ’ or ‘ S ’ based on the arrangement of the substituents in space ( Figure 10 A). This system has the advantage that it can be applied to molecules with more than one asymmetric carbon atom, with each asymmetric carbon being labelled independently, and it is directly related to chemical structure. It is important to note that in molecules with more than one asymmetric carbon, not all the possible stereoisomers are enantiomers. Consider a molecule with two R asymmetric carbon atoms. In the enantiomer (the mirror image), these two asymmetric carbon atoms will both be S . However, there are two other stereoisomers in which only one of the two asymmetric carbon atoms is S ; these two molecules are not mirror images of the first. Stereoisomers that are not mirror images of each other are referred to as diastereomers.

Optical isomerism

( A ) Illustration of the application of the Cahn–Ingold–Prelog rules for describing the configuration of chiral centres. In the Cahn–Ingold–Prelog system, the four substituents around the asymmetric carbon atom are assigned a priority based on three rules: (i) consider the first atom in each substituent, highest priority is given to the atom with the highest atomic number; in case of isotopes, a higher atomic mass gives a higher priority. (ii) If two substituents have the same first atom, move away from the asymmetric carbon to the next bonded atom until a difference is reached. (iii) If the substituent contains a double or triple bond, then the atom farthest from the asymmetric carbon counts two or three times respectively. The molecule is then drawn with the lowest priority substituent at the back (into the page). If the priority of the other three substituents increases clockwise, the centre is assigned ‘ R ’ stereochemistry, otherwise it is ‘ S ”. ( B ) All natural proteinogenic amino acids are the L -form under the Fischer rules, when using the Cahn–Ingold–Prelog rules the natural form of cysteine is the R isomer, this is in contrast with the other amino acids, exemplified by serine, which is the S isomer.

In biochemistry the ‘ d ’ and ‘ l ’ nomenclature, originally developed by the German chemist Emil Fischer, is still widely used to describe amino acids and sugars. In this system, the assignment is made by comparing the structure of a molecule to glyceraldehyde. In the Fisher notation, this makes all natural amino acids ‘ l ’, however in the Cahn–Ingold–Prelog system the naturally occurring isomer of cysteine is R -cysteine, while all others are the S -form ( Figure 10 B).

In a biological chemical reaction, an enzyme must be able to specifically recognize its substrate, and this occurs through matching of the 3D structure of the substrate to that of the enzyme active site (for more detail on active sites see [ 5 ]). For this reason, the chirality of a molecule has a huge influence on its biological activity. Typically, an enzyme will catalyse a reaction with only one of a pair of enantiomer; the other enantiomer has the wrong shape to make favourable non-covalent interactions with the enzyme-binding site. This is often important in drug design as many drugs are chiral molecules. For example, ibuprofen exists as both R and S isomers ( Figure 11 A). Only the S -form is active, however the body converts the R -form into the S -form and so the mixture of both enantiomers is effective in pain relief [ 6 ]. Similarly, the drug thalidomide ( Figure 11 A) exists as both R and S isomers which can be interconverted in the body. In this case, however, while the R -form is an effective sedative the S -form causes severe birth defects.

Chiral drugs and sugars

( A ) The drugs ibuprofen and thalidomide both exist as R and S isomers. In each case, the R and S isomers can be interconverted in the body and have different biological functions. ( B ) Illustration of the different representations of the glucose molecule. The linear form of glucose can be represented by a skeletal structure or a Fischer projection; the cyclic form, by a skeletal structure or a Haworth projection.

Specialist representations for molecules with many chiral centres

Although the majority of organic molecules relevant to biochemistry are drawn using the skeletal representation, there are some classes of molecules for which other representations are favoured. As we will discuss in more detail later, sugars can exist either in a straight chain or ring form. The straight chain form of a sugar is often depicted as a Fischer projection, while the ring form is often shown using a Haworth projection. Many different stereoisomers of sugars occur in nature, and the Fischer and Haworth projections were developed to make it easy to distinguish between stereoisomers. For example, the different representations of d -glucose (C 6 H 12 O 6 ) are shown in Figure 11 B.

Thermodynamics

Thermodynamics aims to understand whether or not a chemical reaction will happen. In answering this question, three quantities are commonly considered: enthalpy, H ; entropy, S ; and the Gibbs free energy, often simply referred to as free energy, G . Enthalpy is a measure of the total heat content of a system. For a chemical reaction the change in enthalpy, ΔH , is related to factors such the number of bonds that are made and/or broken. When ΔH for a chemical reaction is negative, heat is given out and the reaction is called exothermic; conversely when ΔH is positive the system absorbs heat and the reaction is termed endothermic. Entropy is a measure of the disorder of a system; the more disordered the system the higher its entropy. The change in entropy for a chemical reaction, ΔS , will be positive if the disorder increases, for example when ice melts allowing the water molecules to move more freely. Changes in entropy govern whether a chemical reaction will occur; the second law of thermodynamics states that the entropy of the universe always increases in a spontaneous process. The problem with using this definition directly is that it is difficult to think about what happens to the universe as a whole when we are looking at one isolated chemical reaction; this is where the concept of free energy is useful. We consider the reaction and its solvent as the system . The change in the free energy of a system is defined in terms of the changes in enthalpy and entropy of the system:

where, T is temperature in Kelvin. The free energy of the system is related to the entropy of the universe by the equation:

It can therefore be seen that in a spontaneous process the free energy of a system will decrease, i.e. ΔG must be negative. It is important to note that in chemical terms, spontaneous means ‘thermodynamically allowed’; a thermodynamically allowed reaction might not take place if, for example the energy barrier to the reaction (see Kinetics section) is too high.

The actual free energy change that takes place when reactants are mixed together depends upon physical and environmental conditions such as the concentration and physical state of reactants and the pressure and temperature of the system. Therefore, in order to be able to compare the magnitude of free energy changes for different reactions, we define a set of standard conditions; the standard symbol ‘°’ is used to indicate this. The standard symbol ‘°’ implies that all species present in the reaction are in their standard states : gases at a pressure of 1 bar; pure solid; pure liquid; solutions at a concentration of 1 mol dm −3 . Importantly, the standard symbol does not imply any particular temperature. As the magnitude of a free energy change depends upon temperature it is important to state the temperature at which the value of the standard change applies.

The standard free energy change for a chemical reaction, Δ G °, is the change in free energy for reactants combined in molar stoichiometric amounts according to a balanced chemical equation if the reactants were converted completely into products. Consider, for example the formation of water from hydrogen and oxygen:

The standard free energy change is for one mole of hydrogen gas reacting with half a mole of oxygen gas to form one mole of liquid water, with all species present in their standard state under standard conditions.

Chemical equilibrium

Standard free energy changes refer to reactions that proceed to completion and take place under conditions that are far removed from those experienced in biological systems, where reactions typically involve micromolar rather than molar quantities. What relevance do standard free energy changes have for biology? Standard free energy changes are enormously useful because they can be used to predict to what extent a reaction will take place in a chemical equilibrium .

All reactions are reversible; if we the consider the system:

The ⇌ sign indicates that both the forward reaction (A + B combining to form C + D) and the reverse reaction (C + D combining to form A + B) occur. Although, all reactions are theoretically reversible, under certain conditions either the forward or reverse reaction may predominate to the extent that the other reaction can be neglected. Reversible reactions proceed until the concentrations of the species present cease to change with time; it is said that the system has reached chemical equilibrium . Importantly, at equilibrium the concentrations of reactants and products are constant not because the forward and reverse reactions have stopped (static equilibrium) but because the rate of the forward reaction is equal to the rate of the reverse reaction (dynamic equilibrium). The equilibrium constant, K , (often referred to as K c in schools) is related to the concentrations of species at equilibrium and is constant for a reaction at a given temperature. In general, for the reaction:

The values for K can vary widely from reaction to reaction. If K has a large value (i.e. K >>1), then at equilibrium the concentration of products C and D will be larger relative to the concentrations of reactants A and B, and the reaction is said to be product favoured or the equilibrium lies far to the right. If K has a small value (i.e. K <<1), then at equilibrium the concentrations of reactants A and B will be larger relative to the concentrations of products; this type of reaction is said to be reactant favoured or the equilibrium lies far to the left .

The equilibrium constant for a chemical reaction is related to the standard free energy change for the reaction, Δ r G °, by the equation:

where, R is the molar gas constant: 8.314 J mol K −1 , T is the temperature in Kelvin, ln is the natural logarithm.

Rearranging this equation to make K the subject gives:

Thus, Δ r G ° tells us the value of the equilibrium constant and, in turn, how far the reaction lies to the left or the right. For example, if Δ r G ° is large and negative, K will be a large positive number and the reaction will favour the products.

Equilibrium in living systems; flux and coupled reactions

In biological systems, reactions do not occur in isolation but are a part of complex and interconnected metabolic pathways. In a metabolic pathway, the product of one reaction is immediately used as a reactant in the next; this creates a state of flux. In such a pathway, the concentrations of products and reactants are constantly changing. For some reactions in the pathway, the concentrations of reactants and products are close to the equilibrium values, while for many reactions the concentrations lie very far from their equilibrium values. Reactions in a metabolic pathway that are far from equilibrium can be important points for control of metabolic flux within the pathway.

Many biochemical reactions, such as formation of the bond between two amino acids in a protein, are unfavourable in isolation. For example, the standard free energy change for the formation of an amide bond in the simplest dipeptide glycine–glycine at 37°C is 15 kJ mol −1 ; and the associated equilibrium constant is 0.00297 [ 7 ], thus the equilibrium strongly favours the reactants. In order to drive the reaction forward, biochemical systems often couple reactions with a positive free energy change to those with a large negative free energy change. One reaction with a large negative free energy change that is very commonly used is the hydrolysis of ATP, which has a standard free energy change of –30 kJ mol −1 at 37°C. When the hydrolysis of ATP is coupled to the formation of an amide bond, the free energy change for the system becomes –15 kJ mol −1 , and so we would expect the coupled reaction to favour the products. Importantly, coupling reactions together does not involve just having the two reactions happen together at the same time; the free energy released through ATP hydrolysis has to be captured and used to drive forward the other reaction. This capture can be, for example through causing a conformational change in an enzyme or through direct modification of the chemicals involved in the unfavourable reaction (see section on Nucleophilic substitution at a carbonyl ).

Thermodynamics refers to whether or not a reaction will be spontaneous; kinetics refers to whether a reaction will occur at an appreciable rate. In a chemical reaction, existing bonds break while new ones are formed. The transient species that occur along the reaction pathway are high in energy; the point at which the energy is highest is called the transition state or activated complex . The energy which is required in order to form the transition state is called the activation energy . The activation energy may be thought of as a barrier which must be overcome by reacting molecules as they collide in order for the reaction to proceed to the formation of products.

In a chemistry laboratory, the rate of a chemical reaction may be changed by altering certain properties of the system. Increasing the concentrations of the reactants (e.g. reducing particle size for solids or increasing the pressure for reactions involving gases) raises the probability of a collision between reactants and hence increases the rate of reaction. By increasing the temperature, the kinetic energy of the reactant molecules is increased. As a result, collisions between reactant molecules are more energetic such that the activated complex is more likely to form. Unfortunately, these changes are not usually possible in biology.

Addition of a catalyst can also enhance the rate of a chemical reaction. In this case, the catalyst provides an alternative route/mechanism for the reaction that involves a lower activation energy ( Figure 12 ). Importantly, the activation energy for the reverse reaction is also lowered by a catalyst. Thus, a catalyst speeds up the rate at which the equilibrium between reactants and products can be attained but the position of the equilibrium is not changed by the catalyst. Catalysis is essential for biological reactions as the concentrations of reactants in living systems are generally very small (often micromolar to millimolar range), and the temperature at which the majority of such systems operate is relatively low such that the rates of reaction would be extremely slow without any other influences. Enzymes are very efficient catalysts which ensure that the chemical reactions involved in metabolism proceed at a useful rate. For further discussion on enzyme catalysis, see [ 5 ].

Reaction co-ordinate for an uncatalysed compared with enzyme-catalysed reaction

A hypothetical energy profile for the reaction of a substrate (S) forming product (P) in the absence of catalysis is shown in black, while the hypothetical profile for the same reaction in an enzyme (E) catalysed reaction is shown in grey. In the absence of an enzyme, there is a large activation energy ( E a uncat ). In the enzyme-catalysed reaction the enzyme forms a complex with the substrate (ES) and the product (EP) and lowers the energy of the highest energy species on the reaction pathway, resulting in a lower activation energy ( E a enz ).

An acid is an H + ion or proton donor, while a base is an H + ion acceptor. Understanding which biological molecules are acids and which are bases can be important in predicting a variety of behaviours in biological systems, for example in determining catalytic mechanisms. Acids and bases can be strong or weak. When a strong acid or base is added to water, these species are almost completely ionized (dissociated). In contrast, a weak acid or base is only partially ionized on addition to water. Weak acids and bases are more relevant in biochemistry.

Consider ethanoic acid, more commonly called by its non-IUPAC name acetic acid, which is only partially dissociated in aqueous solution:

For acetic acid, the equilibrium lies well to the left such that the concentration of undissociated acetic acid (CH 3 COOH) is much greater than that of H + ions or acetate ions (CH 3 COO − ). The equilibrium constant for this reaction indicates the extent to which the dissociation occurs; the equilibrium constant for acid dissociation reactions is often called the acid-dissociation constant, K a . Considering a general acid as HA:

The acid-dissociation constant for acetic acid at 25°C is 1.76 × 10 −5 , therefore a 0.1 mol dm −3 solution of acetic acid is only 1.3% ionized. The species remaining after a proton has dissociated from an acid is referred to as its conjugate base. For example, the acetate ion is the conjugate base of acetic acid; acetic acid and acetate are referred to as a conjugate pair.

Acetic acid is one of the many acids containing the –COOH or carboxylic acid functional group. Many carboxylic acids are present in biological systems and importantly commonly serve as H + donors during enzymatic catalysis. Similarly, the conjugate base of the carboxylate ion can act as a proton acceptor in base-catalysed enzyme reactions.

pH and p K a

The concentration of H + in aqueous systems is typically very low. For example, the concentration of H + in pure water at 25°C is 10 −7 mol dm −3 . The pH scale is a convenient way of representing very small concentrations; by definition:

Acid dissociation constants have a very large range and analogous to pH, the quantity p K a is defined:

One reason for using pK a is that this makes it easy to work out to what extent an acidic species will be protonated at a given pH. The relation between pH and p K a is known as the Henderson–Hasselbalch equation:

where, HA is an acid and A – is its conjugate base. Without considering specific concentrations, using this equation we can see that if the pH of a solution is equal to the p K a of the acid, then the concentration of the acid form will equal that of the conjugate base. Similarly, at a pH considerably below the p K a the acid form, HA, will dominate, while at a pH considerably above p K a the conjugate base, A − , will dominate.

Several amino acids found in proteins have ionizable side chains; knowledge of typical p K a s of the functional groups in these amino acids allows us to predict the ionization state at physiological pH. In a protein, the side chain of aspartic acid, for example typically has a p K a of ~3.5; at physiological pH, we would expect this group to be ionized/deprotonated.

Interestingly, although we can use typical p K a values as a crude approximate of how a particular amino acid side chain will behave in a protein, in some cases the p K a of that side chain can vary wildly from the typical value. This is because the 3D structure of a protein can create a local environment in which a proton can be lost or gained more readily. Consider the aspartate side chain mentioned above; if there is a positively charged amino acid side chain in the vicinity, then the deprotonated state with its negative charge will form more readily. The majority of the p K a values for aspartic acid side chains in proteins reported in the literature are within ±1 of the average value. The lowest reported p K a is however 0.5 and the highest 9.2 [ 8 ].

A buffer is a solution that maintains a relatively constant pH even upon addition of an acid or a base. Buffers typically consist of a weak acid and a salt of its conjugate base. The weak acid or conjugate base can absorb additions of OH − or H + allowing the pH of the solution to remain approximately constant. Consider the pH of 1 mol dm −3 buffered solution containing 0.25 moles of acetic acid and 0.25 moles of acetate. Since the solution contains equal amounts of a weak acid and its conjugate base, the pH is equal to the p K a of the weak acid, 4.75 in this case. When 0.05 moles of a strong acid is added to the buffer, the H + from the strong acid will react with the acetate ion in the buffer, creating more acetic acid and water. This will cause the total amount of acetate to decrease to 0.20 moles and the total amount of acetic acid to increase to 0.30 moles. Using the Henderson–Hasselbalch equation, we find that the new pH of the solution is 4.57, a change in just 0.18 pH units when 0.05 moles of strong acid is added to the buffer. In contrast, adding the same 0.05 moles of strong acid to 1 l of pure water causes the pH to change from 7.00 to 1.32, a change of 5.68 pH units.

A buffer has its greatest pH buffering capacity when the concentration of the weak acid is equal to the concentration of its conjugate base, and when the desired pH of the solution is within one pH unit of the p K a of the weak acid. For example, consider making an acetate buffer with pH of 4.50. As the desired pH is below the p K a of acetic acid (4.75), the Henderson–Hasselbalch equation predicts that we will need 1.78 times as much acetic acid as acetate ion in the solution. This solution will still have large amounts of both acetic acid and acetate in solution to react with added acid or base to keep the pH of the solution stable. However, if the desired pH of solution is 7.00, then the calculated ratio of acetic acid to acetate is 0.0056, meaning there would be practically no acetate ions in the solution. If a strong acid was added to this solution, the pH would change dramatically.

Maintaining a constant pH is vital to many biological processes. Metabolic pathways depend upon the catalytic activity of enzymes that contain many ionizable functional groups. As described above, changing the pH can alter the protonation state of functional groups in the active site of the enzyme altering its activity. One important buffering system for maintaining intracellular pH, typically between 6.9 and 7.4 for most cells, involves protonation of a modified histidine side chain. Free histidine itself is not a good candidate for an intracellular buffer as the concentration of free histidine in cells is typically low and the p K a of its imidazole group (6.0) is greater than one pH unit away from the typical pH range in a cell. However, in the dipeptide anserine, the p K a of the imidazole nitrogen in the side chain of the methyl histidine is raised to 7.0 making it an ideal candidate for an intracellular buffer ( Figure 13 ).

Anserine buffering

( A ) A schematic titration curve for anserine, with ( B ) an illustration of the species present in the reaction mixture during the titration. Anserine has three groups that can exist in both protonated and unprotonated forms: a carboxylic acid, an imidazole nitrogen and an amine. At the beginning of the titration, all the three groups are protonated and the predominant species in the reaction mix is (1). As base is added, the pH approaches the p K a for the first ionizable group, the carboxylic acid, and species (2) begins to form resulting in a plateau in the titration curve. Once the majority of molecules are in form (2), the pH will begin to rise again, before the second plateau occurs due to the formation of species (3). It is the equilibrium between species (2) and (3) that is relevant at biological pH. The final plateau occurs when the fully deprotonated species (4) is formed.

Enzymes enhance the rate of a chemical reaction by providing an environment in which intermediate species along the reaction pathway are stabilized, however, the mechanisms by which chemical reactions occur obey the same principles as those performed in a chemistry lab. We can therefore learn a great deal about a biochemical reactions by studying the mechanisms of the reactions in the absence of an enzyme. Here, we outline some of the most commonly occurring reactions in biological chemistry.

Nucleophilic substitution reactions at saturated carbon centres

Carbon atoms forming one or more single bonds to electronegative atoms are susceptible to attack from electron-rich nucleophiles. In the final product of a nucleophilic substitution reaction , the nucleophile forms a covalent bond with the carbon atom and replaces a ‘leaving group’ (often designated by the symbol X) ( Figure 14 A). Whether or not a nucleophilic substitution reaction will take place depends, in part, on whether ‘X’ is a good leaving group, but what is meant by a good leaving group? When the bond between the carbon atom and X breaks, it does so heterolytically, with both the electrons in the bond being transferred to X. A good leaving group is therefore one that can readily accommodate these electrons. In many cases, the leaving group will become negatively charged, so good leaving groups are often those that will form stable anions.

Nucleophilic substitution at a saturated carbon centre

( A ) Illustration of a nucleophilic substitution with a negatively charged nucleophile and a leaving group. It should be noted that the nucleophile may be a neutral molecule with a lone pair of electrons and that the leaving group may also be neutral (as seen in ( C )). ( B ) Common leaving groups in biological chemistry. (C) Many biological methylation reactions take place via a nucleophilic attack on S -adenosyl methionine. In this diagram, the leaving group is shown in blue and the nucleophile in red.

The coenzyme A anion, with a negative charge on sulphur and the phosphate anion, with the negative charge delocalized over several atoms, are very common leaving groups in biological chemical reactions ( Figure 14 B). One of the most widely occurring nucleophilic substitution reactions in biochemistry is transfer of a methyl group from S -adenosyl methionine to a nucleophile ( Figure 14 C). Many different nucleophiles are reactive towards this molecule. For example, in the synthesis of the amino acid methionine the nucleophile is a sulphur atom; in the synthesis of norepinephrine the nucleophile is a nitrogen atom; and the degradation of dopamine includes nucleophilic attack on S -adenosyl methionine by an oxygen atom. In each case, the S -adenosyl methionine is a positively charged substrate and the leaving group is the neutral S -adenosyl homocysteine group.

Carbonyl chemistry

The carbonyl group plays a central role in many biological chemical reactions, in particular those involving the making and breaking of carbon–carbon bonds. As mentioned earlier, the carbonyl carbon atom carries a partial positive charge, making it susceptible to nucleophilic attack by electron-rich species. The first step in the reaction of a nucleophile with a carbonyl carbon atom is the formation of a new covalent bond, resulting in a species with four substituents around the central carbon atom ( Figure 15 A). What happens after this initial attack depends on which other atoms are bonded to the carbonyl carbon atom in the starting material. One possibility is that the negatively charged oxygen atom will form a bond to a proton to form an alcohol, and the central carbon atom will have four substituents in the final product. Another possibility is that the carbonyl group will reform, displacing one of the other three substituents. A final possibility is that the attacking nucleophile is itself a good leaving group, and so the reaction reverses. Which of these possibilities occur depend on whether the carbonyl group in the starting material is bonded to a good leaving group, the reactivity of the nucleophile and on the relative thermodynamic stability of the starting materials and products.

Nucleophilic addition at a carbonyl group

( A ) Nucleophilic attack on a carbonyl group results in a species with four substituents around a central carbon atom (a tetrahedral species). Whether or not this species reacts further depends upon the nature of the X and Y groups and the nucleophile. ( B ) If X and Y are not good leaving groups and the nucleophile is also a poor leaving group, then the tetrahedral species will be the final product.

Nucleophilic addition to a carbonyl

When a nucleophile reacts with an aldehyde or a ketone, there are two possible outcomes: addition of the nucleophile or reversal of the reaction to regenerate the starting material. Addition, rather than substitution, occurs because neither ‘H – ’ nor ‘R – ’ (with a negatively charged carbon atom) are good leaving groups ( Figure 15 B). An addition reaction usually involves a strong nucleophile and can be very useful in forming new carbon–carbon bonds. The reverse reaction occurs when the nucleophile is itself a good leaving group, for example water or an alcohol. This usually results in an equilibrium between the carbonyl compound and the addition product. When this reaction is carried out in the organic chemistry laboratory, an acid catalyst is used to enhance the reactivity of the carbonyl group ( Figure 16 A). The addition of an alcohol to an aldehyde or ketone is responsible for the cyclization of sugars. In cells, an enzyme catalyses sugar cyclization and the attack on the carbonyl group is made by an alcohol in the same molecule ( Figure 16 B).

Reversible addition at a carbonyl group

( A ) If X and Y are not good leaving groups but the nucleophile is a good leaving group, then the reaction may reverse, as seen in the acid-catalysed reaction of a ketone with an alcohol. This reaction also occurs with aldehydes and the tetrahedral product is called a hemiacetal. ( B ) Formation of hemiacetal occurs during the cyclization of glucose.

Nucleophilic substitution at a carbonyl

If the carbonyl carbon in the starting material is bonded to a good leaving group, then nucleophilic substitution reactions are a possibility. In substitution reactions, the incoming nucleophile makes a bond with the carbonyl carbon and the bond between the carbonyl carbon and the leaving group breaks. These processes do not happen simultaneously; the addition of a nucleophile to a carbonyl compound always forms a species with four substituents around the central carbon first ( Figure 17 A). Nucleophilic substitution at a carbonyl is the key reaction in protein synthesis, resulting in a carboxylate group being converted into an amide. The formation of the amide does not occur by nucleophilic attack of the amine of one amino acid on the carboxylate group of another, however. First, in order to make the reaction energetically favourable, it must be coupled to the hydrolysis of ATP. Second, from a mechanistic perspective, the carboxylic acid/carboxylate group does not have a good leaving group and so is a poor substrate for nucleophilic substitution. Third, the amino acid needs to be attached to a biological macromolecule (a tRNA) in order to make sure that the correct amino acid is added to the growing peptide chain. In order to meet these requirements, a peptide bond is made in a series of three reactions ( Figure 17 B).

Nucleophilic substitution at a carbonyl group

( A ) If the carbonyl subjected to a nucleophilic attack has a good leaving group, then nucleophilic substitution is possible. The substitution reaction proceeds via an obligatory tetrahedral species. ( B ) Three nucleophilic substitution reactions are important in the formation of an amide bond between two amino acids. The first reaction involves nucleophilic substitution at a phosphate group and the second nucleophilic reactions involve substitution at a carbonyl. In the first reaction, the carboxylate group attacks a phosphate of ATP releasing pyrophosphate – two phosphate groups connected together via a bridging oxygen atom – and attaching AMP to the carboxylate group. This step is energetically favourable and converts one of the oxygen atoms of the carboxylate group of the amino acid into a good leaving group. In the second reaction, the amino acid is loaded on to the tRNA ready for protein formation. In the third reaction, the enzyme ensures that the amino group of the attacking amino acid is not protonated, and this group then carries out a nucleophilic attack on another tRNA–conjugated amino acid.

Enol and enolate formation

Many carbonyl compounds show a form of isomerism known as tautomerism, in which a proton moves from one position in the molecule to another. In general, the equilibrium lies towards the carbonyl compound, although there are some exceptions. Enol and enolate formation can be catalysed by either acid or base in vitro ; in vivo this isomerism is catalysed by an enzyme, and the amino acid side chains making up the active site act as acids and bases during the catalytic cycle ( Figure 18 A). In biological chemistry, keto–enol tautomerism takes place during the interconversion of different types of sugars ( Figure 18 B). It is also very important in the formation of new carbon–carbon bonds as enols and enolates can act as carbon nucleophiles. We can understand why this is if we consider the resonance structure of the enolate anion which has a negative charge on a carbon atom ( Figure 19 ). Although the resonance structure does not exist as a stable molecule, it helps us to understand why this particular carbon can be a nucleophile. Although carbon with a negative charge is usually very unstable, in an enolate the bonding is actually very similar to that seen in a carboxylate – the negative charge is not localized on the carbon atom but is instead delocalized over three atoms, which has a stabilizing effect. This reaction is very important in the synthesis and degradation of both sugars and fatty acids.

Keto–enol tautomerism

( A ) Illustration of a ketone and its enol form, and the mechanism of this reaction in the presence of acid and base. For the majority of species, the equilibrium lies towards the ketone rather than the enol. ( B ) The tautomerization of glucose gives an ene–diol, because there is an alcohol group adjacent to the carbonyl (diol, two alcohols). If, in the reverse reaction the carbonyl group is formed at the alcohol adjacent to the original carbonyl in the starting material, then an isomer of glucose, fructose, is formed.

Carbon–carbon bond formation with enols/enolates

( A ) Resonance structures of an enolate illustrating that there is high electron density on both the oxygen atom and one of the carbon atoms in this molecule. ( B ) When an enolate attacks a carbonyl group through its nucleophilic carbon, a new carbon–carbon bond is formed. If there is a good leaving group, X, on the tetrahedral intermediate species then a second carbonyl group can form, otherwise the tetrahedral species can gain a proton to form an alcohol. ( C ) The reaction of dihydroxyacetone phosphate (red) and glyceraldehyde-3-phosphate (blue) to form fructose-1,6-bisphosphate is a key reaction in glucose synthesis, while the reverse reaction occurs in the breakdown of glucose (glycolysis).

Oxidation and reduction of organic compounds

Oxidation of a compound involves loss of electrons and reduction involves gain of electrons during a chemical reaction. You will probably be most familiar with this process in inorganic chemistry, where metal ions change their oxidation state through addition or loss of electrons. Organic molecules can be oxidized or reduced, however the electrons are often transferred indirectly, for example through transfer of ions. This indirect transfer often takes the form of hydrogen atoms; in the oxidation of an alcohol to a ketone, two hydrogen atoms are lost by the alcohol, with the concomitant loss of two electrons in the process. The electrons are often passed to an acceptor molecule as a hydride ion H – . A hydride ion is very unstable and is a very poor leaving group, however in this case, the enzyme ensures that the acceptor molecule is perfectly positioned to receive the hydride in the enzyme active site. There are a number of different hydride acceptor molecules in biochemical systems, a very common one is NAD + ( Figure 20 ).

Organic reduction reactions

NAD + is the acceptor molecule for hydride ion in many organic oxidation reactions. It also donates hydride ion in reductions of, for example, carbonyl derivatives.

There are some processes that are essential for life for which non-carbon-based chemistry is required. In particular, life makes use of the varied properties of metals. For example, the ability of the transition metals to exist in multiple oxidation states is often exploited in biology to aid the catalysis of oxidation reduction reactions; transition metals often act as electron carriers in these reactions.

The process of photosynthesis includes electron transfer steps utilizing transition metals. One example is the use of ferredoxins to transfer electrons from photosytem I to the protein responsible for making the reducing agent NADPH, which is necessary for reducing CO 2 to form glucose. Ferredoxins are proteins that contain one or more clusters of iron ions and sulphide ions, and some of the iron ions in these clusters are able to cycle between the Fe 3+ and Fe 2+ state.

In photosynthesis, the ferredoxin protein contains a cluster with two iron and two sulphur ions, designated as [2Fe2S]. In the oxidized state, both the iron ions are Fe 3+ . When ferredoxin docks with reduced photosystem I, one of the iron ions receive an electron and become Fe 2+ . The ferredoxin diffuses to the next protein in the chain (ferredoxin:NADP + reductase), where the Fe 2+ acts as an electron donor. A second example illustrating the importance of transition metals in photosynthesis is the manganese-containing cluster in photosystem II. In this case, the oxidation state of the manganese ions change; essentially acting like a biological capacitor building up positive charge, driven by light. This charge is then neutralized by taking the electrons from water, producing oxygen (for a further discussion see [ 9 ]).

The ability of metal ions to co-ordinate non-metal ligands is also used extensively within biology in order to maintain specific protein structures. For example, zinc ions are used in zinc finger proteins to support a structure that can recognize and bind to DNA. In addition, the variation in charge, size and preferred pattern of co-ordination among different ions allows them to be recognized by biological molecules. This in turn allows metal ions to be used as signalling molecules in biological systems, for example calcium ions in muscle contraction. In addition the solubility of metals within water provides life with both challenges and opportunities. Clearly, the levels of these metals must be carefully controlled to stop unwanted precipitation, but this process can be harnessed to enable life to produce hardened structures such as shells and bones. Overall, it is the different binding properties of metals compared with carbon, along with the ability to exist in multiple oxidation states which metal ions bring to the diversity of chemistry in life.

Life carries out an astonishing variety of chemistry under mild conditions and with enormous efficiency. Here, we have provided a brief overview of the essential principles that govern the reactions of life. We hope that interested readers will refer to some of the suggested resources which provide more detail on why chemical reactions occur.

This article is a reviewed, revised and updated version of the following ‘Biochemistry Across the School Curriculum’ (BASC) booklet: Essential Chemistry for Biochemistry by E.J. Wood and A. Myers (1991). For further information and to provide feedback on this or any other Biochemical Society education resource, please contact [email protected] . For further information on other Biochemical Society publications, please visit www.biochemistry.org/publications .

J.L.K. and K.A.S. thank Professors Raymond Dwek and Nicole Zitzmann for their support.

The authors declare that there are no competing interests associated with the manuscript.

This work was supported by the Lerner-Fink Scholarship (to J.L.K.) and the Oxford Glycobiology Endowment (to K.A.S.).

Open Access for this article was funded by the Biochemical Society.

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The molecular vista: current perspectives on molecules and life in the twentieth century

Mathias grote.

1 Institut für Geschichtswissenschaften, Humboldt-Universität zu Berlin, Friedrichstraße 191-193, 10099 Berlin, Germany

2 Max Planck Institute for the History of Science, Boltzmannstraße 22, 14195 Berlin, Germany

Angela N. H. Creager

3 Department of History, Princeton University, 129 Dickinson Hall, Princeton, NJ 08544 USA

Soraya de Chadarevian

4 UCLA Department of History, 6265 Bunche Hall, Los Angeles, CA 90095-1473 USA

5 ICI Berlin Institute for Cultural Inquiry, Christinenstraße 18/19, Haus 8, 10119 Berlin, Germany

Gina Surita

6 Department of History, Program in History of Science, Princeton University, 129 Dickinson Hall, Princeton, NJ 08544 USA

Sarah E. Tracy

7 Technoscience Research Unit, Faculty of Information, University of Toronto, 140 St. George Street, Toronto, ON M5S 3G6 Canada

This essay considers how scholarly approaches to the development of molecular biology have too often narrowed the historical aperture to genes, overlooking the ways in which other objects and processes contributed to the molecularization of life. From structural and dynamic studies of biomolecules to cellular membranes and organelles to metabolism and nutrition, new work by historians, philosophers, and STS scholars of the life sciences has revitalized older issues, such as the relationship of life to matter, or of physicochemical inquiries to biology. This scholarship points to a novel molecular vista that opens up a pluralist view of molecularizations in the twentieth century and considers their relevance to current science.

Laboratory versus data? Historiography of life sciences beyond the gene

Michel Morange once remarked on the absurdity of trying to define molecular biology in abstract or transhistorical terms:

Molecular biology is not merely the description of biology in terms of molecules—if this were the case, it would not only include biochemistry, but also all those nineteenth-century studies in chemistry or in physiology, that led to the characterization of biological molecules. With such a broad definition, even Pasteur would have been a molecular biologist! (Morange 1998 , p. 1, see also Morange 2020 , p. 2).

Twenty-five years have passed since this reflection was first published. And while the inclusion of Louis Pasteur in the history of molecular biology still seems ludicrous, the boundaries of the field still—or once again—seem fluid. One reason for this may be that two decades after the completion of the Human Genome Project, a longue durée view of molecularization enables scholars to better situate the molecular gene as part of a broader endeavor to transform the material basis of biological research into large, portable data sets (Stevens 2013 ; Richardson and Stevens 2015 ; Leonelli 2016 ; Strasser 2019 ). The prominence of DNA sequencing and omics-approaches has increased the scale and pace of research through automation and bioinformatic analysis, and has produced a situation in which “doing life science” has become nearly synonymous with algorithmic thinking and computerized work (Roosth 2017 ; Liu 2017 ). Historiographically and historically, we have reached a point at which it is possible to think about this computationally-inflected history of genomics and proteomics as separate from, but related to, the history of molecular biology.

This historiographical review leads us up to the perceived data- and omics-centric present. It also emphasizes the points of historical friction and divergence from its dominance: behind the language of genetics, the dirty wet lab side of research has always provided a foundation. This admittedly presentist perspective sheds light on some historiographical absences that can prompt new research. Work on the technological frontier of the molecular life sciences includes contemporary philosophical reflections on tinkering with life in the age of synthetic biology and ethnographies of in silico or structural biology (Helmreich 1998 ; Myers 2015 ). Sophia Roosth ( 2017 ) has argued that there is a cohort of synthetic biologists who actively try to automate and suppress genetics at the wet bench. The question is whether it works (de Chadarevian 2018 ).

The genealogies of undervalued laboratory tinkering tap into biophysics, biochemistry, bioenergetics, colloid and surface chemistry, microscopy, and other endeavors that address the terra incognita in between cells and molecules. Even in “classical” molecular biology, including protein chemistry and structural studies (crystallography and electron microscopy) of proteins, viruses, or muscle fibers, chemistry was clearly a leading concern, although rarely trumpeted. In fact, John Kendrew, Max Perutz, Fred Sanger, Linus Pauling, and Gunther Stent were all chemists of some sort (Serafini 1989 ; de Chadarevian 2002 ; James 2007 ; Creager 2009 ). Relatedly, the range of physicists who participated in biology needs reevaluation. This task of reevaluation invites additional reflection upon how the narrative choices of historians might have reinforced the gendering of laboratory workspaces (Creager and Morgan 2008 ; Abir-Am 2014 ; Santesmases 2020 ), or restricted our purview to the west and the Global North in contrast to more transhemispheric understandings (Mignolo 2011 ; Mateos and Suárez 2014 ; Ling and Jiang 2019 ).

These aforementioned sensibilities, with which we now survey the history of the molecular life sciences, lead us to a vista that exhibits different sites of work and labor apart from university laboratories. It also includes diverse geographic regions, institutions, and actors that previously have been marginalized in historical narratives. In this essay, we re-examine the past in order to offer specific insights about areas that have been underattended to as part of the history of post-war molecular biology. In doing so, we opt to bypass the discourse of molecular biology’s disciplinarity by attending to perspectives that broaden the vista, since the longstanding preoccupation with the field’s origins is finally in the rearview mirror. 1 Despite proclamations of a paradigm-shifting epigenetic revolution or of molecular biology's “evaporation” as a discipline (Rheinberger 2009 ), its “vapors”—the representations, imagery, metaphors, and scale of explanatory reasoning—are omnipresent in the life sciences, science education, and cultures of popular science. 2

While the ancient question of how to relate ideas of “life” to those of “matter” persists, the rapid growth of molecular knowledge since the end of the nineteenth century has vastly outstripped the growth of integrative or synthetic conceptions of life (Liu 2019 ). Far from meta-scientific issues such as reductionism or the origin of life, the contributions summarized below highlight a set of questions about nutrition, energy, physiology, microstructure, and animal economy that predate or were concurrent with molecular biology. Below, we outline recent studies which, when examined together, suggest a continuation of research along these lines throughout the twentieth century, even during the perceived half-century of the hegemony of molecular genetics. Our own research questions that have arisen as a result of responding to the dominance of DNA narratives thus revise past narratives as much as they scope out an unexplored molecular vista. This essay resulted from a panel at the International Society for the History, Philosophy and Social Studies of Biology 2019 meeting in Oslo. Participants were Soraya de Chadarevian, Mathias Grote, Daniel Liu, Lisa Onaga, Gina Surita, and Sarah Tracy (presenting a paper co-authored with Hannah Landecker); Angela Creager commented.

Structures of “Molecules” and “Life”

Historians have long examined how scientists have come to understand life on a molecular scale by focusing on their methods for visualizing and manipulating structural entities. 3 In his paper, Daniel Liu addressed the question of “structure” in the longer history of molecularization reaching back into the nineteenth century, by analyzing efforts of a heterogenous group of scientists seeking to understand cells at submicroscopic scales. The apotheosis of this branch of molecular biology might be found in the use of electron microscopy to decipher the molecular structures of subcellular organelles, especially the mitochondria, Golgi apparatus, endoplasmic reticulum, and so on (see Rasmussen 1997a ). This research continues as an auxiliary, rather than a central, part of cell biology and anatomy. The electron microscope was an instrumental extension of a research program that, prior to WWII, was often referred to as research on “fine structure” or even “sub-microscopic morphology,” using indirect imaging methods such as x-ray diffraction of whole cells in conjunction with polarized light microscopy and other inferential techniques in colloid chemistry. Rather than trying to understand atomic positions within a single molecule, as was the case in x-ray crystallography of protein and nucleic acid fibers, some of these researchers used x-ray diffraction diagrams of whole cells to show how layers of proteins and lipids were arranged, determine how thick each layer was, and obtain clues about the chemical identity of each substance composing these layers. As biophysicist Frank Schmitt put it, this technique could illuminate the “dimensions, configurations, and orientation of molecules” in cells (Schmitt 1944 , p. 1587). This method was further combined with polarization microscopy, allowing analysis of birefringence and refractive index, revealing the “presence of oriented constituents in tissue systems, together with the direction of orientation, shape, crystallinity, partial volume and refractive index of the oriented components” (Schmitt 1944 , p. 1587). X-ray diffraction was computationally intensive but yielded absolute dimensional and geometrical measurements, while polarization microscopy provided a more holistic picture of optical anisotropy, molecular orientation, and hints about material identity—and could be performed much more quickly and easily than x-ray techniques. The use of polarization microscopy to discern submicroscopic structures has a history stretching back to Carl Nägeli’s studies of starch granules in the 1860s, and was given new life once it was combined with early x-ray powder diffraction studies of cellulose in the 1920s.

Mathias Grote’s paper highlighted the continued impact of the combination of chemical and structural thinking in the colloidal “world of neglected dimensions” (Olby 1986 , quoting Wolfgang Ostwald) in the molecular life sciences post-1970. Grote outlined a genealogy of molecular and colloidal practices in the chemiosmotic model of cellular energy generation that Peter Mitchell had proposed in the 1960s, which conceptually and practically linked interwar surface and membrane studies with late-twentieth-century bioenergetics. Grote showed how membrane-enclosed vesicles (liposomes) allowed biochemists from the early 1970s onward to reconstitute cellular structure in the test tube in order to spatialize biochemical reactions, such as the transfer of ions across a membrane. He argued that reconstitution—a concept and practice for the functional assembly of biological molecules into supramolecular structures—illustrates an interplay of modelling, understanding, and making components of life. Reconstitution, formerly employed in virus research (Creager 2002 ), and the resulting “plug-and-play” biology more generally, gained traction after 1980, and aimed at putting together and making work molecular components. Membranes, forming from lipids in aqueous solution by self-organization and by being re-formed, partitioned and inherited during the cellular life cycle, thus display exciting physico-chemical dynamics that have the potential to shake molecular biological certitudes. In the test tube, re-made membranes were fused with isolated proteins, analyzed by microscopy, studied functionally, and put together in different combinations, using synthesized RNA/DNA or recombinant proteins. Plug-and-play has also become fundamental to today’s synthetic biology, where the idea has been extended and commodified, e.g., in biobricks or ongoing projects to create synthetic cells (Grote 2019 ). Moreover, plug-and-play has brought physiology and molecular biology (of physical, chemical, and genetic sorts) into close contact, and has in fact rendered them indistinguishable in many fields, bridging gaps between the molecular, supramolecular/colloidal, and cellular levels of structure. The bacterial cell wall, both as an ultramicroscopic structure and an object of metabolic research in the context of penicillin action, is a related, earlier example for such border crossings. Its research has juxtaposed fields addressing different levels of biological organization and helped create a “chemistry of shape” (Santesmases 2016 , p. 29).

Even the history of genetics, and not just that of DNA, is not immune to the historical importance of structural methods and entities. Soraya de Chadarevian showed that starting in the late 1950s cytogeneticists were able to correlate hereditary diseases with alterations of chromosome structure that were visible under the light microscope, offering important diagnostic tools to medical geneticists. Even though molecular biologists predicted for decades that sequence data would displace older techniques relying on observations of chromosomes under microscopes, that day never arrived. Rather, cytogeneticists proved able to visualize complex mutational events that are hard to identify using the tools of molecular biology. As it turns out, many of these complex chromosome-level mutations (such as translocations and inversions) are key genetic signatures of cancer cells, making cytogenetics especially valuable in oncology and cancer research. Her work suggests that scientific fields do not simply operate as political regimes that replace each other; more often, specialties continue on parallel tracks, and the public visibility of one discipline need not spell the demise of others (de Chadarevian 2020 ). The dynamic three-dimensional structure of chromatin fibers is gaining new salience in studies of epigenetic regulations in the cell, indicating that even in the field of molecular genetics there is much to gain from a perspective that includes structural and cellular next to environmental considerations (Landecker 2015 ).

In addition, methods of structure determination display a greater heterogeneity and topics such as the relation of molecular and cellular structure a greater continuity than previously thought. Beyond x-ray crystallography of protein or DNA, membranes, chromosomes, and other subcellular structures were analyzed by a variety of such methods. Furthermore, new methods, such as fluorescence microscopy, optical and magnetic spectroscopies, or cryo-electron microscopy were developed; the latter has been in the limelight since the 2017 Nobel prize to Jacques Dubochet, Joachim Frank, and Richard Henderson (Grote 2019 ; Reinhardt 2017 ).

Lively economies, metabolism, and interdisciplinarity

While this focus on structure has provided scholars with a useful vantage point, there are other avenues into the lesser-visited corners of the history of twentieth-century biology: these include studies of the prolific use of metaphors in the life sciences (besides the gene-as-code-metaphor); the history of lower-status fields, such as, nutrition science; and analyses of biological phenomena such as symbiotic relationships. The study of metaphorical language illuminates how historical actors understood and communicated conceptualizations of life as well as its experimentally known underpinnings (Keller 1995 ). The most commented-upon metaphor in molecular biology has been that of genetic material as “code” or “information,” perhaps demonstrated most comprehensively by Lily Kay’s Who Wrote the Book of Life? (2000). 4 But as Andrew Reynolds ( 2018 ) has shown, cell biologists drew on a range of other metaphors. Since the nineteenth century, cells have been cast variously as “organisms,” “citizens,” “machines,” and “factories” (Reynolds 2018 ; Nyhart and Vienne 2017 ). Gina Surita’s paper examined the metaphors used by biochemists to understand subcellular life. For example, the history of bioenergetics can be understood as the gradual articulation of the cell as a kind of “economy,” in which the universal energy “currency” of ATP (adenosine triphosphate) circulated in order to “pay” for various life-sustaining, energy-requiring metabolic reactions (Gina Surita, Ph.D. dissertation in progress). Drawing upon older, physiological invocations of the metaphor of the “animal economy,” twentieth-century bioenergeticists localized this notion of a vital economy to the cell, where, incidentally, the vast majority of energy exchanges were thought to take place in the cell cytoplasm, outside the nucleus.

Neglected approaches to “molecules” and “life” also come into view when historians survey low-status areas of research. Nutrition is especially important in this regard—the association of life with chemical transformation and metabolism runs from nineteenth-century animal economy right through the industrialization of food production in the twentieth century (Kamminga and Cunningham 1995 ; Stoff 2012 ). Following the researchers who determined basic nutritional requirements for humans, animals, and plants reveals a bundle of practical ties between molecular analysis and agriculture (Kollmer 2020 ). As Lisa Onaga ( 2021 ) shows, the biochemical study of the nutritional requirements of silkworms in Japan grew in the 1930s as an outcome of falling silk prices in the country. Scientists in Japan began to investigate how to supplement limited supplies of mulberry leaves with nutrient extracts of mulberry and soybeans to feed silkworms. At the same time, many farmers converted mulberry acreage to other crops and many others emigrated to the puppet-state of Manchuria to work on soybean plantations. The manufacture of molecularly-formulated artificial silkworm feed involved chemical studies of nutritional factors responsible for physiological feeding behaviors of silkworms, and contributed to the broader history of making artificial media for cultivating laboratory organisms.

Historians of biology have also begun analyzing how theories of metabolism fed into the development of chemically-defined media and animal feed (Landecker 2016a , 2019 ). These histories connect to the vibrant literature on model organisms, with its focus on how animal and plant systems serve as laboratory exemplars for understanding life, and they also reflect more recent attention to scientific infrastructures as well as issues of animal welfare. 5 For example, scholars involved in the Animal Research Nexus, a 5-year, Wellcome Trust-funded collaborative project in the UK, have been undertaking an interdisciplinary and reflexive examination of how laboratory biomedical researchers implement animal models while weighing matters of protecting and promoting both human health and animal welfare (Friese 2018 ; Davies et al. 2020 ). These inquiries dovetail with what could be called the molecularlization of agriculture and animal husbandry. Be they mice or sheep, twentieth-century investigations of molecular life processes in agriculture and biomedical settings relied on certain configurations of infrastructure, finance, and labor (García-Sancho and Myelnikov 2019 ).

One of the limitations of earlier studies of molecular biology has had to do with how sociocultural, political, and economic dimensions were brought into the narratives as a consequence of how those studies were attuned primarily to molecular biological narratives. Dominic Berry’s work on synthetic biology illustrates a newer approach to integrating the history of molecular biology with histories of technology and business. By using material and discursive analysis to study how objects, institutions, machines, journals, companies, human actors, and molecules related to other, he ascertains the significance of multiple meanings of “making” DNA. His strategy to locate a lesser-known, engineering-centered narrative serves to avoid uncritically reproducing the sanctity of DNA (Berry 2019 ). Such cognizance also works against the commonplace narrative that the commercialization of biology mainly concerns biotechnology since the 1980s. Historical research emerging from collaborative projects such as “Organisms and Us” at the University of Adelaide highlights how organisms of longstanding commercial relevance have been gaining scientific attention while the molecular pathways of organisms adapted to extreme environmental conditions have offered strategic biological appeal to scientists (Dietrich et al. 2020 ; Green et al. 2018 ). 6

The food and agriculture aspects of molecular biology have also given rise to discussions about molecularization as a strategy within Science & Technology Studies (STS) that advocates for greater attention to key molecules as regulators. Aligned with these calls for diversification of which objects count as historically relevant agents, Sarah E. Tracy has examined research that aimed to measure the effects of the flavor chemical monosodium glutamate (MSG). While glutamates are naturally occurring compounds, they are also common food additives, and their effects have been a source of controversy since the late-1960s. Tracy’s paper pointed to the striking compartmentalization of research on MSG. On the one hand, diabetes researchers have relied upon the obesogenic effect of large doses of MSG upon newborn mice. On the other hand, food scientists have pursued the potentially advantageous appetitive and digestive effects of MSG, based on findings from adult rodent models (Tracy and Landecker, forthcoming). Key connections between the flavor industry’s objectives and the risk of metabolic disorder due to food additives have been overlooked as a result of the compartmentalization of research and the complexity (e.g., the developmental and species variability) of glutamate’s bioactivity (Tracy 2018 , 2019 ). As Tracy remarked, recent attention in biomedicine to metabolic disorder illustrates that genes are not the only informational actors in the body (Landecker 2011 , 2016b ). 7

The effects of molecules like glutamate in rodent studies of digestion and metabolism point us to emergent historical and philosophical debates on how to study so-called “postgenomic” biology. The epigenetic processes that inform holobiontic relationships in organisms have generated much attention that have called into question not just the stability of DNA but the notion of the organism itself (Dupré and O’Malley 2013 ; Baedke et al. 2020 ). 8 Feminist scholars of bioscience, for instance, have suggested including the metabolic contributions of bacteria to the biological processes of other organisms, including humans, in order to recognize the historical roles of bacteria in scientific knowledge production (Roy 2018 ). Furthermore, studies of social epigenetics linked to diet and analyzed relative to disease susceptibility have injected scholarship with new evidence that affords the articulation of relational ideas of race, environment, and society (Baedke and Nieves Delgado 2019 ). Molecular-scale understandings of metabolism also help broaden our historical perspective into the historical sciences. Disciplines like zooarchaeology are increasingly building context- and actor-dense reconstructions of the evolution of humans, the animals they have depended upon (for nourishment, clothing, tools, and labor), and the microbiota hosted by them both. New fields like bioarchaeogenetics have sought to understand the relationships among animals, plants, and microorganisms from micro- to macro-scales by integrating genomic and proteomic diagnostic tools into existing methods in biology and ethnography (Sykes 2014 ; Hendy et al. 2018 ). 9 Historians of the life sciences face a special responsibility to interrogate how such technologies are used to articulate longue durée bioarchaeological narratives, even as we are called upon to contribute to this new and exciting area of scholarship.

Rethinking biology and the physical sciences

In various ways, the recent scholarship we highlight illustrates the importance of the physical sciences, and especially chemistry, to biology. By contrast, conventional accounts attribute the origins of molecular biology to physicists who turned their attention to solving the secret of life, especially after the devastating use of atomic bombs at the end of World War II. Attesting the critical role of physicists was always partisan, and even though Francis Crick and Maurice Wilkins certainly read and were inspired by Schrödinger’s What is Life? (Rasmussen 1997b ), they came away with different conceptions of how biology and physics ought to engage each with other. Although this scholarship illustrates the enduring importance of the physical sciences to biology, we also want to highlight that we are defining “the physical sciences” much more broadly than most older histories of molecular biology did: we understand the physical sciences to include the chemical and material sciences as well. In this we are following a similar shift happening in other areas of the history of physics more broadly: For example, Schwartz ( 2004 , 2008 ) has shown how the central role of chemists in Manhattan Project was marginalized by a combination of the project's secrecy and post-Hiroshima public relations, while Joe Martin ( 2018 ) has shown how solid state physicists and materials scientists navigated the shifting divide between physics and chemistry after World War II. By contrast, the narrative of physicists revolutionizing biology after reading Schrödinger and in the aftermath of Hiroshima was a mythology that drew a bright line between a valorized “pure” atomic or quantum physics and an impure “applied” or industrial physics and chemistry (Delbrück 2007 ; Reinhardt 2018 ). In fact, the influx of physical scientists into biology in the twentieth century was always as much from chemistry as physics, and it has long been noted that the adoption of tools and approaches from the physical sciences by biologists themselves also heavily tilted towards chemistry (Kohler 1976 ; Abir-Am 1982 ; Keller 1990 ; Kay 1993 ; Deichmann 2007 ). 10 More than two decades ago, Rasmussen ( 1997b ) persuasively argued that biologists pulled physics in as much as physicists pushed into biology; in some cases, the physics involved had turned out to be so esoteric and strange that historians and philosophers have struggled to make sense of it (Sloan and Fogel 2011 ). Paying attention to practice rather than rhetoric in biology brings into view chemical tools, techniques, and approaches, as well as those from physics that are not prominent in the historiography, such as the solid-state physics, surface science, and microstructural studies (Martin 2018 ).

Biologists often turn to chemistry for very pragmatic reasons. As Angela Creager ( 2017 ) observed in an essay on her “chemical reaction” to this historiography, when biologists handle, purify, stabilize, and analyze the stuff of living organisms they generally find themselves doing chemistry—even when they don’t remark on this in their publications. This insight seems especially apt for the other quite variegated cases that composed our panel. Not all of these papers were about biochemistry, but even colloidal chemistry made an appearance in the session, and twentieth-century nutritional studies relied heavily on analytical chemistry (on organic chemistry in hormone, vitamin, and enzyme studies, see e.g. Stoff 2012 ; Schürch 2017 ).

Earlier historical works in the field included a great deal of chemistry but did not always emphasize it. Take, for instance, the profound historical studies of virus research, structural biology of DNA and proteins at Cambridge, or protein synthesis published around the millennial heyday of the Human Genome Project (Creager 2002 ; de Chadarevian 2002 ; Rheinberger 1997 ), which show how thinking in terms of code and information has always been intertwined with material, chemical analyses, especially when it comes to hands-on laboratory practice. The attention to chemical thinking and working is even more prominent in literature from before this period, such as work on physiology and biochemistry by Holmes ( 1974 ) or Robert Kohler ( 1982 ). Together with new interest in materials and metabolism (Landecker 2011 , 2019 ), chemistry has become an unintended beneficiary of recent historiographical developments. This aligns with Creager ( 2017 ), who observes that focusing on materials-centered research challenges a strong divide between biology and chemistry. 11 In this sense, the recurrent importance of structures in the papers by our panelists reflects more than acknowledging the essential chemical toolbox. That said, the focus on structures also closes the loop with respect to the historiography of molecular biology and physics that we mentioned at the outset, by making the chemistry in the “structural school” of molecular biology more visible (Kendrew 1967 ).

In the historiography of molecular structural research there is much to be done, if only to gain a firmer grasp of the sheer extent of molecularization: It was not only DNA and globular proteins whose structures were resolved down to the atomic level to such great fanfare. For example, as Karl Matlin ( 2016 ) has recently shown, theories of the structure of mitochondria were essential in deciphering the spatially complex synthesis of ATP. Similar studies have yet to be done on the history of transport theories, chloroplasts and related plant plastids, the cytoskeleton, etc. Far from merely cataloging the histories of different structures, such studies can illustrate the diverse ways in which theories of structure and theories of physiological or biochemical function have been forged. After all, every living thing, every part of every living thing, and every derivative of every living process can be said to be ultimately made of molecules! To what extent this brings us full circle back to the problem of a definition of molecular biology highlighted by Morange is a question we do not want to resolve here. Our point is that we believe our vista of the molecular life sciences must be broadened to accurately capture the history of twentieth century biology.

As some of our contributors made clear, rethinking molecular biology’s history is about more than the borders with the physical sciences or the importance of heredity. Much new work is looking closely at research previously deemed “old-fashioned” or marginal—in part because the now seemingly central problems of (largely genetic) data, computing, or even machine learning in biology have achieved a significant degree of abstraction and independence from the material problems that historically occupied molecular biologists. As Soraya de Chadarevian asked off-handedly during the session, “Is this because genomics is no longer a chemistry-adjacent science?” Additional questions raised by the audience highlighted interests and concerns about the intersections between molecular biology and industry. We believe these types of questions and discussions are neither features limited to our panel nor circumstantial, but indicate broader shifts afoot. 12 Personalized medicine, nutrition, genetics, animal science, even cosmetics, are back in view (e.g. Boniolo and Nathan 2017 ). The efforts in several quarters to better understand feeding, whether of silkworms, cells, or people, are especially striking (Landecker 2016a ).

The new attention to lower-status fields can also help make visible scientists of different socioeconomic or educational backgrounds, and from underrepresented groups, genders, and ethnicities in the doing of science, including molecular biology. The foregrounding of marginalized actors, be they women, persons of color, or scientists from the Global South, can help diversify the curricula that is used to teach about the history and philosophy of the life sciences to new generations and thus impact whose histories are included and how those histories are remembered (Spanier 1995 ; Wailoo 2001 ; Wailoo and Pemberton 2006 ; Zulueta 2009 ; Hartley and Tansey 2015 ; Onaga 2014 ; Jiang and Stevens 2015 ; Nelson 2016a ). 13 Attention to the subordination that is associated with scut work may help us understand the gendered dimension of categorizing “ideal” scientists as those who work with their minds, not their bodies. Molecular equivalents of this gendered division of labor abound; as Hannah Landecker ( 2013 , p. 501) has observed, the “housekeeping” functions of the cell, often used to describe the various processes associated with cellular metabolism, have long been demarcated from and seen as subsidiary to the “executive” genetic functions of the cell. 14 Overcoming these norms takes deliberate attention. Much as historians of technology have highlighted women in computing (e.g., Hicks 2018 ), it is necessary to recognize the names and faces of those women who have worked in molecular biology, from Margaret O. Dayhoff and her work on computational sequencing (Strasser 2010 ) to technicians and postdoctoral fellows (e.g., Martha Chase and Susan Berget) who contributed to path-breaking laboratory experiments. Detailed recognition of these individuals alongside women scientists like Esther Lederberg, June Almeida, Marie Maynard Daly, Mildred Cohn, Louise Chow, Susan Lindquist, Tu Youyou, Carol Greider, and Elizabeth Blackburn, to name a few, can thus draw out the harder realities of where the molecular labor resides in biology. This, in turn, can allow us to map the intellectual power dynamics among many more players in just as many neglected corners of science.

Since the development of high-throughput genome sequencing in 2006, scientists have been increasingly doing cutting-edge biology in silico, relegating the bench to background labor (Stevens 2013 ; Roosth 2017 ). Looking back, somewhere in between the characterization of DNA and in silico biology, there was a great deal of laborious, dirty—and at times dangerous—wet lab research that is easily forgotten next to burnished double helices and computers. Equally invisible are the geographies and labor involved in procuring biological material used in research, for example, the viscera of pork from industrial farms, or the re-using of kitchen waste (Blanchette 2020 ; Ibáñez Martín and de Laet 2018 ). These issues of life and labor are the other side of the coin to philosophical questions that have arisen about how biology as data, models, and changing norms of experimentation give rise to personalized medicine and the associated problems that can ensue (Ratti 2020 ; Green et al. 2019 ). The material work, due to its often idiosyncratic and sometimes personal character linked to specific availabilities, skills, equipment or traditions, also helps to further trace the “power of place,” such as by research carried out in very specific labs or beyond them, in companies, hospitals, or the field, and take into account the impact of the economic and political conditions of the molecular life sciences (Fischer 2013 ; Curry 2014 ; Santesmases and Suárez Diáz 2015 ). In addition to the fact that the landscape of the history of molecular biology is more diverse and messier than previously imagined, some fellow scholars are venturing beyond its marked paths altogether. To be sure, much of the terrain remains unmapped, but this suite of papers provided a few snapshots of the vistas for other scholars interested in how scientists sought to relate molecules and life in the twentieth century.

Acknowledgements

We thank Sabina Leonelli and two anonymous referees for their insightful comments. Şahin Balur and Katharina Hillermann are thanked for their assistance with the bibliography.

Open Access funding enabled and organized by Projekt DEAL.

1 Excellent work on this point exists already (e.g., Abir-Am 1992 ; de Chadarevian and Gaudillière 1996 ; de Chadarevian and Kamminga 1998 ); de Chadarevian and Rheinberger 2009 ).

2 See Morange ( 2020 , pp 1–8; 13–22; 369–386).

3 For example, tools from the physical sciences used to develop the Tiselius electrophoresis apparatus not only separated proteins within a mixture, but enabled their photographic visualization. See Kay ( 1988 ).

4 For a different perspective on the “Book of Life Metaphor,” see Brandt ( 2005 ).

5 For key examples of recent and established model organisms literature, see Kohler ( 1994 ), Rader ( 2004 ), Endersby (2007), Ankeny ( 2010 ), Leonelli and Ankeny ( 2013 ), Ankeny and Leonelli ( 2019 ). On animal welfare, see Nelson ( 2016b ).

6 The project investigators are Rachel Ankeny, Sabina Leonelli, and Michael Dietrich. See https://arts.adelaide.edu.au/organisms-and-us/ .

7 For related discussion, see Oudshoorn ( 1990 ), Burian ( 1996 ).

8 The German Research Foundation (DFG)-funded research group Return of the Organism (PI: Jan Baedke) at Ruhr University Bochum investigates an array of questions surrounding organisms known at their genomic levels by bringing philosophical, historical, and social and anthropological methods into conversation. https://rotorub.wordpress.com/ .

9 The Proteins and Fibers working group at the MPIWG, including our co-authors Lisa Onaga, Daniel Liu, and Soraya de Chadarevian, has been examining the historical implementation of molecular biology and chemistry in interdisciplinary scientific fields that assay samples derived from animal materials and body parts (e.g., teeth, bones, hides). Historical reconstruction of the science contributing to “textbook” cases of gene-culture co-evolution such as lactase persistence is, for example, facilitated by analyzing how changing suites of methods and technique came to include microbial information. See https://www.mpiwg-berlin.mpg.de/research/projects/proteins-and-fibers-scaffolding-history-molecular-signatures .

10 The role of the Rockefeller Foundation, and especially Warren Weaver, in encouraging interdisciplinary research that brought the between the physical and life sciences—which really meant involved bringing the former into the latter—has been well-documented and critiqued since Robert Kohler’s classic 1976 article on Weaver.

11 Reinhardt ( 2018 ) makes this point more broadly for how a materials-based approach to history shows that much of modern science is saturated with chemistry, even when it is not explicitly connected with that discipline.

12 The 2019 formation of the Biological Engineering Collaboratory, spearheaded by Dominic Berry, Janella Baxter, and Robert Smith, for instance, has established a network of scholars guided by a mission to encourage integrative studies of biology and technology: https://www.bioengcoll.org/ .

13 This concern is revisited in “Statement on Racialized Violence and Resources,” HSS Graduate and Early Career Caucus (blog), July 13, 2020, https://hssgecc.wordpress.com/statement-on-racialized-violence/ . It lays out “a vision of a diverse profession, which includes not only promoting the voices and scholarship of more Black historians of science, but also calling on white and non-black historians of science to recognize their own privilege.” Within the history of the molecular life sciences, recognizing that dominant historical narrative accounts of DNA have routinely elided scientists of color (be they students, technicians, or full professors) will be a key strategy toward the articulation of underknown histories.

14 This contrasts nicely with Evelyn Fox Keller’s analysis of “master molecule” narratives in descriptions of gene action, in which executive metaphors are prominent (Keller 1995 ).

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Contributor Information

Mathias Grote, Email: [email protected] .

Lisa Onaga, Email: ed.gpm.nilreb-gwipm@aganol .

Angela N. H. Creager, Email: ude.notecnirp@regaerc .

Soraya de Chadarevian, Email: ude.alcu.yrotsih@naiveradahc .

Daniel Liu, Email: ten.uil-nad@nad .

Gina Surita, Email: ude.notecnirp@atirusg .

Sarah E. Tracy, Email: moc.liamg@dhpimamu .

• Abir-Am PG. The discourse of physical power and biological knowledge in the 1930s: A reappraisal of the rockefeller foundation’s ‘Policy’ in molecular biology. Social Studies of Science. 1982; 12 :341–382. [ PubMed ] [ Google Scholar ]
• Abir-Am PG. The politics of macromolecules: Molecular biologists, biochemists, and rhetoric. Osiris. 1992; 7 :164–191. doi: 10.1086/368709. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Abir-Am, P. G. (2014) Crafting Women Scientists of the 1970s: An Ego-Histoire of a Lost Generation. In: Govoni, Paola, and Zelda Alice Franceschi. Writing about Lives in Science: (Auto)Biography, Gender, and Genre (pp. 223–259). Vandenhoeck & Ruprecht, 2014.
• Ankeny RA. Historiographic reflections on model organisms: or how the Mureaucracy may be limiting our understanding of contemporary genetics and genomics. History and Philosophy of the Life Sciences. 2010; 32 (1):91–104. [ PubMed ] [ Google Scholar ]
• Ankeny RA, Leonelli S. Organisms in Experimental Research. In: Dietrich MR, Borrello ME, Harman OS, editors. Handbook of the Historiography of Biology. Cham, Switzerland: Springer International Publishing AG; 2019. pp. 1–25. [ Google Scholar ]
• Baedke J, Nieves Delgado A. Race and nutrition in the new world: Colonial shadows in the age of epigenetics. Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences. 2019; 76 :101175. doi: 10.1016/j.shpsc.2019.03.004. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Baedke J, Fábregas-Tejeda A, Nieves Delgado A. The Holobiont concept before Margulis. Journal of Experimental Zoology Part B: Molecular and Developmental Evolution. 2020; 334 (3):149–155. doi: 10.1002/jez.b.22931. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Berry DJ. Making DNA and its becoming an experimental commodity. History and Technology. 2019; 35 (4):374–404. doi: 10.1080/07341512.2019.1694125. [ CrossRef ] [ Google Scholar ]
• Blanchette, A. (2020). Porkopolis: American animality, standardized life, and the factory farm . Durham: Duke University Press.
• Boniolo G, Nathan MJ, editors. Philosophy of Molecular Medicine: Foundational Issues in Research and Practice. New York: Routledge; 2017. [ Google Scholar ]
• Brandt C. Genetic code, text, and scripture: metaphors and narration in German Molecular Biology. Science in Context. 2005; 18 (4):629–648. doi: 10.1017/S0269889705000694. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Burian RM. “The Tools of the Discipline: Biochemists and Molecular Biologists”: A comment. Journal of the History of Biology. 1996; 29 (3):451–462. doi: 10.1007/BF00127384. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Creager ANH. The Life of a Virus: Tobacco Mosaic Virus as an Experimental Model, 1930–1965. Chicago: University of Chicago Press; 2002. [ Google Scholar ]
• Creager ANH. Phosphorus-32 in the phage group: Radioisotopes as historical tracers of molecular biology. Studies in History and Philosophy of the Biological and Biomedical Sciences. 2009; 40 :29–42. [ PMC free article ] [ PubMed ] [ Google Scholar ]
• Creager ANH. A chemical reaction to the historiography of biology. Ambix. 2017; 64 (4):343–359. doi: 10.1080/00026980.2017.1412136. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Creager ANH, Morgan GJ. After the double helix. Isis. 2008; 99 (2):239–272. doi: 10.1086/588626. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Curry HA. From garden biotech to garage biotech: Amateur experimental biology in historical perspective. The British Journal for the History of Science. 2014; 47 (3):539–565. [ Google Scholar ]
• Davies G, Gorman R, Greenhough B, Hobson-West P, Kirk RGW, Message R, Myelnikov D, Palmer A, Roe E, Ashall V, Crudgington B, McGlacken R, Peres S, Skidmore T. Animal research nexus: A new approach to the connections between science, health and animal welfare. Medical Humanities. 2020; 46 (4):499–511. doi: 10.1136/medhum-2019-011778. [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• de Chadarevian S. Designs for Life: Molecular Biology after World War II. Cambridge: Cambridge University Press; 2002. [ Google Scholar ]
• de Chadarevian S. Things and data in recent biology. Historical Studies in the Natural Sciences. 2018; 48 (5):648–658. doi: 10.1525/hsns.2018.48.5.648. [ CrossRef ] [ Google Scholar ]
• de Chadarevian S. Heredity under the Microscope: Chromosomes and the Study of the Human Genome. Chicago: University of Chicago Press; 2020. [ Google Scholar ]
• de Chadarevian S, Gaudillière J-P. The tools of the discipline: biochemists and molecular biologists. Journal of the History of Biology. 1996; 29 (3):327–330. doi: 10.2307/4331402. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• de Chadarevian S, Kamminga H. Molecularizing Biology and Medicine: New Practices and Alliances, 1910s–1970s. Amsterdam: Harwood; 1998. [ Google Scholar ]
• de Chadarevian, S., & Rheinberger, H.-J. (2009). Introduction. Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences . Special Issue: Disciplinary histories and the history of disciplines: the challenge of molecular biology, 40 (1), 4–5. 10.1016/j.shpsc.2008.12.001. [ PubMed ]
• Deichmann U. “Molecular” versus “colloidal”: controversies in biology and biochemistry. Bulletin of the History of Chemistry. 2007; 32 :105–118. [ Google Scholar ]
• Delbrück M. A Physicist Looks at Biology. In: Cairns J, Stent GS, Watson JO, editors. Phage and the Origins of Molecular Biology. Cold Spring Harbour Laboratory of Quantitative Biology: Cold Spring Harbour; 2007. pp. 9–22. [ Google Scholar ]
• Dietrich MR, Ankeny RA, Crowe N, Green S, Leonelli S. How to choose your research organism. Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences. 2020; 80 :101227. doi: 10.1016/j.shpsc.2019.101227. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Dupré, J., & O’Malley, M. A. (2013). Varieties of Living Things: Life at the Intersection of Lineage and Metabolism. In S. Normandin & C. T. Wolfe (Eds.), Vitalism and the Scientific Image in Post-Enlightenment Life Science, 1800–2010 (pp. 311–343). Netherlands: Springer. 10.1007/978-94-007-2445-7_13
• Fischer MMJ. Biopolis: Asian science in the global circuitry. Science, Technology and Society. 2013; 18 (3):379–404. doi: 10.1177/0971721813498500. [ CrossRef ] [ Google Scholar ]
• Friese C. Co-producing Animal Models and Genetic Science. Routledge Handbook of Genomics: Health and Society; 2018. pp. 273–282. [ Google Scholar ]
• Fruton JS. Molecules and Life: Historical Essays on the Interplay of Chemistry and Biology. New York: Wiley-Interscience; 1972. [ Google Scholar ]
• García-Sancho M, Myelnikov D. Between mice and sheep: Biotechnology, agricultural science and animal models in late-twentieth century Edinburgh. Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences. 2019; 75 :24–33. doi: 10.1016/j.shpsc.2019.01.002. [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Green S, Dietrich MR, Leonelli S, Ankeny RA. ‘Extreme’ organisms and the problem of generalization: Interpreting the Krogh Principle. History and Philosophy of the Life Sciences. 2018; 40 (4):65. doi: 10.1007/s40656-018-0231-0. [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Green, S., Carusi, A., & Hoeyer, K.. (2019). Plastic diagnostics: The remaking of disease and evidence in personalized medicine. Social Science & Medicine , 112318. 10.1016/j.socscimed.2019.05.023 [ PMC free article ] [ PubMed ]
• Grote M. Membranes to Molecular Machines. Active Matter and the Remaking of Life. Chicago: The University of Chicago Press; 2019. [ Google Scholar ]
• Hartley JM, Tansey EM. White coats and no trousers: Narrating the experiences of women technicians in medical laboratories, 1930–90. Notes and Records of the Royal Society of London. 2015; 69 (1):25–36. [ PMC free article ] [ PubMed ] [ Google Scholar ]
• Helmreich S. Silicon Second Nature: Culturing Artificial Life in a Digital World. Berkeley: University of California Press; 1998. [ Google Scholar ]
• Hendy J, Welker F, Demarchi B, Speller C, Warinner C, Collins MJ. A guide to ancient protein studies. Nature Ecology & Evolution. 2018; 2 (5):791–799. doi: 10.1038/s41559-018-0510-x. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Hicks, M. (2018). Programmed Inequality: How Britain Discarded Women Technologists and Lost its Edge in Computing . Cambridge: MIT Press.
• Holmes FL. Claude Bernard and Animal Chemistry: The Emergence of a Scientist. Cambridge, MA: Harvard University Press; 1974. [ Google Scholar ]
• Ibáñez Martín R, de Laet M. Geographies of fat waste. Or, how kitchen fats make citizens. The Sociological Review. 2018; 66 (3):700–717. doi: 10.1177/0038026117726731. [ CrossRef ] [ Google Scholar ]
• James, J. L. (2007). Naturalizing the chemical bond: Discipline and creativity in the Pauling program, 1927–1942 . (Ph.D. dissertation). Harvard University, Cambridge, Mass.
• Jiang L, Stevens H. Chinese biotech versus international ethics? Accounting for the China-America CRISPR ethical divide. BioSocieties. 2015; 10 :483–488. [ Google Scholar ]
• Kamminga, H., & Cunningham, A. (1995). The Science and Culture of Nutrition, 1840–1940 . Amsterdam & Atlanta GA: Rodopi. [ PubMed ]
• Kay LE. Laboratory technology and biological knowledge: The Tiselius electrophoresis apparatus, 1930–1945. History and Philosophy of the Life Sciences. 1988; 10 :51–72. [ PubMed ] [ Google Scholar ]
• Kay LE. The Molecular Vision of Life: Caltech, the Rockefeller Foundation, and the Rise of the New Biology. New York: Oxford University Press; 1993. [ Google Scholar ]
• Kay LE. Who Wrote the Book of Life? A History of the Genetic Code. Stanford: Stanford University Press; 2000. [ Google Scholar ]
• Keller EF. Physics and the emergence of molecular biology: A history of cognitive and political synergy. Journal of the History of Biology. 1990; 23 (3):389–409. [ PubMed ] [ Google Scholar ]
• Kendrew JC. How molecular biology started. Scientific American. 1967; 216 :141–144. [ Google Scholar ]
• Keller, E. F. (1995). Refiguring Life: Metaphors of Twentieth-Century Biology . Columbia University Press.
• Kohler RE. The management of science: The experience of Warren Weaver and the Rockefeller Foundation Programme in molecular biology. Minerva. 1976; 14 :279–306. [ PubMed ] [ Google Scholar ]
• Kohler RE. From Medical Chemistry to Biochemistry: The Making of a Biomedical Discipline. Cambridge: Cambridge University Press; 1982. [ Google Scholar ]
• Kohler RE. Lords of the Fly: Drosophila Genetics and the Experimental Life . Chicago: University of Chicago Press; 1994. [ Google Scholar ]
• Kollmer, C. A. (2020). From Elephant to Bacterium: Microbial Culture Techniques and Chemical Orders of Nature . Ph.D. dissertation. Princeton: Princeton University.
• Landecker H. Food as exposure: Nutritional epigenetics and the new metabolism. BioSocieties. 2011; 6 (2):167–194. doi: 10.1057/biosoc.2011.1. [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Landecker H. Postindustrial metabolism: Fat knowledge. Public Culture. 2013; 25 (3):495–522. [ Google Scholar ]
• Landecker H. Commentary: The information of conformation. International Journal of Epidemiology. 2015; 44 (4):1107–1108. [ PubMed ] [ Google Scholar ]
• Landecker H. It is what it eats: Chemically defined media and the history of surrounds. Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences. 2016; 57 :148–160. [ PubMed ] [ Google Scholar ]
• Landecker H. The social as signal in the body of chromatin. The Sociological Review Monographs. 2016; 6 (1):79–99. [ Google Scholar ]
• Landecker H. A metabolic history of manufacturing waste: Food commodities and their outsides. Food, Culture & Society. 2019; 22 (5):530–547. doi: 10.1080/15528014.2019.1638110. [ CrossRef ] [ Google Scholar ]
• Leonelli S. Data-Centric Biology: A Philosophical Study. Chicago: University of Chicago Press; 2016. [ Google Scholar ]
• Leonelli S, Ankeny RA. What makes a model organism? Endeavour (New Series) 2013; 37 (4):209–212. [ PubMed ] [ Google Scholar ]
• Ling V, Jiang L. A different kind of synthesis: Artificial synthesis of insulin in socialist China. History and Technology. 2019; 35 (4):453–480. doi: 10.1080/07341512.2019.1694124. [ CrossRef ] [ Google Scholar ]
• Liu D. This is the synthetic biology that is. Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences. 2017; 63 :89–93. doi: 10.1016/j.shpsc.2017.03.002. [ CrossRef ] [ Google Scholar ]
• Liu D. The artificial cell, the semipermeable membrane, and the life that never was, 1864–1901. Historical Studies in the Natural Sciences. 2019; 49 (5):504–555. doi: 10.1525/hsns.2019.49.5.504. [ CrossRef ] [ Google Scholar ]
• Martin JD. Solid State Insurrection: How the Science of Substance Made American Physics Matter. Pittsburgh: University of Pittsburgh Press; 2018. [ Google Scholar ]
• Mateos, G., & Suárez,E. (2014). Mexican physics and life sciences during the Cold War era. In: Medina, E., Marquez, I. and Holmes, C. (Eds.), STS in Latin America: Beyond Imported Magic. Cambridge: MIT Press.
• Matlin KS. The Heuristic of form: Mitochondrial morphology and the explanation of oxidative phosphorylation. Journal of the History of Biology. 2016; 49 (1):37–94. doi: 10.1007/s10739-015-9418-3. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Mignolo WD. The Global South and World Dis/Order. Journal of Anthropological Research. 2011; 67 (2):165–188. [ Google Scholar ]
• Morange M. A History of Molecular Biology. Cambridge MA: Harvard University; 1998. [ Google Scholar ]
• Morange M. The Black Box of Biology. Cambridge: Harvard University Press; 2020. [ Google Scholar ]
• Myers N. Rendering Life Molecular. Durham: Duke University Press; 2015. [ Google Scholar ]
• Nelson A. The Social Life of DNA: Race, Reparations, And Reconciliation After the Genome. Boston, MA: Beacon Press; 2016. [ PubMed ] [ Google Scholar ]
• Nelson N. Model homes for model organisms: Intersections of animal welfare and behavioral neuroscience around the environment of the laboratory mouse. BioSocieties. 2016; 11 :46–66. [ Google Scholar ]
• Nyhart LK, Vienne F. Introduction to special issue: Revolutionary politics and biological organization in nineteenth-century France and Germany. Historical Studies in the Natural Sciences. 2017; 47 (5):589–601. doi: 10.1525/hsns.2017.47.5.589. [ CrossRef ] [ Google Scholar ]
• Olby R. Structural and Dynamic Explanations in the World of Neglected Dimensions. In: Horder TJ, Wittowski JA, Wylie CC, editors. A History of Embryology: Eighth Symposium of the British Society for Developmental Biology. Cambridge: Cambridge University Press; 1986. pp. 175–203. [ Google Scholar ]
• Onaga LA. Ray Wu as fifth business: Deconstructing collective memory in the history of DNA sequencing. Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences. 2014; 46 :1–14. doi: 10.1016/j.shpsc.2013.12.006. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Onaga, L. (2021). A Matter of Taste: Making artificial silkworm food in 20th century Japan. In L. Campos, M. R. Dietrich, T. Saraiva, & C. Young (Eds.) Nature Remade: Engineering Life, Envisioning Worlds . Chicago: University of Chicago Press.
• Oudshoorn N. On the making of sex hormones: Research materials and the production of knowledge. Social Studies of Science. 1990; 20 (1):5–33. [ PubMed ] [ Google Scholar ]
• Rader KA. Making Mice: Standardizing Animals for American Biomedical Research, 1900–1955. Princeton NJ: Princeton University Press; 2004. [ Google Scholar ]
• Rasmussen N. Picture Control: The Electron Microscope and the Transformation of Biology in America, 1940–1960. Stanford: Stanford University Press; 1997. [ Google Scholar ]
• Rasmussen N. The mid-century biophysics bubble: Hiroshima and the biological revolution in America, revisited. History of Science. 1997; 35 (109):245–293. [ PubMed ] [ Google Scholar ]
• Ratti E. ‘Models of’ and ‘Models for’: On the relation between mechanistic models and experimental strategies in molecular biology. The British Journal for the Philosophy of Science. 2020; 71 (2):773–797. doi: 10.1093/bjps/axy018. [ CrossRef ] [ Google Scholar ]
• Reinhardt C. ‘This Other Method’: The dynamics of NMR in biochemistry and molecular biology. Historical Studies in the Natural Sciences. 2017; 47 (3):389–422. [ Google Scholar ]
• Reinhardt C. Introduction to ‘What’s In a Name? Chemistry as a nonclassical approach to the World. Isis. 2018; 109 :559–564. [ Google Scholar ]
• Reynolds AS. The Third Lens: Metaphor and the Creation of Modern Cell Biology. Chicago: University of Chicago Press; 2018. [ Google Scholar ]
• Rheinberger H-J. Toward a History of Epistemic Things: Synthesizing Proteins in the Test Tube. Stanford: Stanford University Press; 1997. [ Google Scholar ]
• Rheinberger H-J. Recent science and its exploration: The case of molecular biology. Studies in History and Philosophy of Biological and Biomedical Sciences. 2009; 40 (1):6–12. doi: 10.1016/j.shpsc.2008.12.002. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Richardson SS, Stevens H. Postgenomics: Perspectives on Biology After the Genome. Durham: Duke University Press; 2015. [ Google Scholar ]
• Roosth S. Synthetic: How Life Got Made. Chicago: University of Chicago Press; 2017. [ Google Scholar ]
• Roy D. Molecular Feminisms: Biology, Becomings, and Life in the Lab. Seattle: University of Washington Press; 2018. [ Google Scholar ]
• Santesmases MJ. The bacterial cell wall in the antibiotic era: An ontology in transit between morphology and metabolism, 1940s–1960s. Journal of the History of Biology. 2016; 49 (1):3–36. [ PubMed ] [ Google Scholar ]
• Santesmases MJ. Women in early human cytogenetics: An essay on a gendered history of chromosome imaging. Perspectives on Science. 2020; 28 (2):170–200. [ Google Scholar ]
• Santesmases MJ, Suárez-Díaz E. A cell-based epistemology: Human genetics in the era of biomedicine. Historical Studies in the Natural Sciences. 2015; 45 (1):1–13. [ Google Scholar ]
• Schmitt FO. Tissue Ultrastructure Analysis: Polarized Light Method. In: Glasser O, editor. Medical Physics. Chicago: The Year Book Publishers; 1944. pp. 1586–1591. [ Google Scholar ]
• Schürch C. How mechanisms explain interfield cooperation: Biological-chemical study of plant growth hormones in Utrecht and Pasadena, 1930–1938. History and Philosophy of the Life Sciences. 2017; 39 (3):16. doi: 10.1007/s40656-017-0144-3. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Schwartz RP. Why did physicists get all the credit: The Smyth report as authorized history of the atomic bomb. Chemical Heritage. 2004; 22 (3):32–33. [ Google Scholar ]
• Schwartz, R. P. (2008). The Making of the History of the Atomic Bomb: Henry Dewolf Smyth and the Historiography of the Manhattan Project . Ph.D. dissertation. Princeton: Princeton University.
• Serafini A. Linus Pauling: A Man and His Science. New York: Paragon House; 1989. [ Google Scholar ]
• Sloan PR, Fogel B. Creating a Physical Biology: The Three-Man Paper and Early Molecular Biology. Chicago: University of Chicago Press; 2011. [ Google Scholar ]
• Spanier B. Im/Partial Science: Gender Ideology in Molecular Biology. Bloomington: Indiana University Press; 1995. [ Google Scholar ]
• Stevens H. Life Out of Sequence: A Data-Driven History of Bioinformatics. Chicago: University of Chicago Press; 2013. [ Google Scholar ]
• Stoff H. Wirkstoffe: Eine Wissenschaftsgeschichte der Hormone, Vitamine und Enzyme, 1920–1970. Stuttgart: Franz Steiner Verlag; 2012. [ Google Scholar ]
• Strasser B. Collecting, comparing, and computing sequences: The making of Margaret O. Dayhoff’s “Atlas of Protein Sequence and Structure”, 1954–1965. Journal of the History of Biology. 2010; 43 (4):623–660. doi: 10.1080/17458927.2017.1420027. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Strasser BJ. Collecting Experiments: Making Big Data Biology. Chicago: University of Chicago Press; 2019. [ Google Scholar ]
• Sykes N. Beastly Questions: Animal Answers to Archaeological Issues. London: Bloomsbury Publishing; 2014. [ Google Scholar ]
• Tracy SE. Delicious molecules: Big food science, the chemosenses, and Umami. The Senses and Society. 2018; 13 (1):89–107. doi: 10.1080/17458927.2017.1420027. [ CrossRef ] [ Google Scholar ]
• Tracy SE. Tasty waste: Industrial fermentation and the creative destruction of MSG. Food, Culture & Society. 2019; 22 (5):1–18. [ Google Scholar ]
• Tracy, S. E., & Landecker, H. (forthcoming). Fat Mice: Revisiting Umami, Monosodium Glutamate, and the Molecular Gut.
• Wailoo K. Dying in the City of the Blues: Sickle Cell Anemia and the Politics of Race and Health. Chapel Hill: University of North Carolina Press; 2001. [ Google Scholar ]
• Wailoo K, Pemberton SG. The Troubled Dream of Genetic Medicine: Ethnicity and Innovation in Tay-Sachs, Cystic Fibrosis, and Sickle Cell Disease. Baltimore: Johns Hopkins University Press; 2006. [ Google Scholar ]
• Zulueta BC. Master of the master gland: Choh Hao Li, the University of California, and science, migration, and race. Historical Studies in the Natural Sciences. 2009; 39 (2):129–170. doi: 10.1525/hsns.2009.39.2.129. [ PubMed ] [ CrossRef ] [ Google Scholar ]

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What is a biology personal statement?

Your biology personal statement should tell the university all about your strengths, skills, experience and career plans.

It should also convey your enthusiasm for the subject, and what aspects of it you enjoy and why.

How do I write a biology personal statement?

It’s a good idea to start your statement with why you want to study biology at university.

Try to talk about what drew you to biology initially - was it a childhood experience, or were you inspired by a family member or a television documentary? Pin this down if you can, as admissions tutors always want to know about your motivations for wanting to study their subject.

Make sure you back up everything with examples, as you need to convince the university that you they should offer you a place on their biology degree over anyone else.

A great biology personal statement should be written clearly and concisely, with a good introduction, middle, and a conclusion. After all, your statement has to stand out from the crowd if your UCAS application is going to be successful.

For inspiration on how to write your own unique statement, take a look at some of our engineering personal statement examples above, as well as our collection of top rated personal statement examples .

What should I include in my biology personal statement?

It’s important to include skills and experience from all areas of your life and try to relate them to hobbies or extracurricular activities if they helped you to build on certain strengths.

Think about how any work experience you have completed might be useful in your degree, e.g. what skills did you learn? were there any parts of it you particularly enjoyed? if so, why?

Make sure you include everything that is relevant to your course, which means you may want to leave off your Grade 6 in piano, or your swimming certificates.

University admissions tutors want to know what you can bring to their department and what value you can add, so every sentence of your personal statement needs to earn its place.

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Home — Essay Samples — Education — Academic Interests — Why I Choose Biochemistry Major: the Path Forward

Why I Choose Biochemistry Major: The Path Forward

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Published: Sep 5, 2023

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The nexus of curiosity and complexity, bridging academia and aspirations, shaping a vision for the future.

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The Basics of General, Organic, and Biological Chemistry

(26 reviews)

David W Ball, Cleveland State University

John W Hill, University of Wisconsin

Rhonda J Scott, Southern Adventist University

Copyright Year: 2011

ISBN 13: 9781453311097

Publisher: Saylor Foundation

Language: English

Formats Available

Conditions of use.

Learn more about reviews.

Reviewed by SATHIAMOORTHY BALASUBRAMANIAN, Chemistry FACULTY, Rochester Community & Technical College on 3/6/23

This text book is adequately comprehensive and covers all chapters of a GOB chemistry course. The content is well organized and explained clearly. Students need to review the practice questions for better grasp of concepts. read more

Comprehensiveness rating: 5 see less

This text book is adequately comprehensive and covers all chapters of a GOB chemistry course. The content is well organized and explained clearly. Students need to review the practice questions for better grasp of concepts.

Content Accuracy rating: 5

Mostly error free and accurate

Relevance/Longevity rating: 5

This text book is highly relevant for GOB course students who need to take this course for Nursing, dental hygiene and other programs.

Clarity rating: 5

Very clear and precise and written in a manner which is easily understood at student's level.

Consistency rating: 5

Consistent for all chapters.

Modularity rating: 5

Each chapter is divided into various sections based on "Learning Objective". Under each section, I like the skill building exercise and practice questions. This way the student can attain mastery in each topic by going through the skill building exercise and solving the practice questions.

Organization/Structure/Flow rating: 5

Well organized meeting the learning objectives of this course in each chapter.

Interface rating: 5

No issues. Easily able to toggle between various chapters, no distortion of diagrams or images.

Grammatical Errors rating: 5

Didn't come across significant grammatical errors

Cultural Relevance rating: 1

Not applicable

I will recommend this for students who need a text book to master topics of GOB. All the chapters which are part of GOB course curriculum are covered in a an easy to understand manner. The application of concepts can be learnt by doing the practice questions under each learning objective. Highly recommended!

Reviewed by Alan Rowe, Adjunct Professor of Chemistry, Tidewater Community College on 7/1/22

Very comprehensive--- Currently pre-Nursing studetns are only required to take the first part of the 2 semester GOB course so only 1/2 of ths text would be used in that course. read more

Comprehensiveness rating: 4 see less

Very comprehensive--- Currently pre-Nursing studetns are only required to take the first part of the 2 semester GOB course so only 1/2 of ths text would be used in that course.

Very nice treatment of chemical concepts at an approprite level

Relevance/Longevity rating: 4

Text is relevant , but It would really benefit from real world examples of the chemical concepts covered, especially those related to healthh care

Good clarity- concise but not overly so

Cosistent form chapter to chapter

Modularity rating: 4

Most chemistry text for GOB are similar-- this one follows that pattern

The material is organized in the manner that I would like to present the information-- one concept follows the next almost seamlessly

no problems here

Seems to read very well using grammatical structure easy for the student to follow

Cultural Relevance rating: 5

no indication of any cultural references at all

The exercises with answers are helpful as well as those without the answers (in the chapter and at the end of chapater problems). Both could be assigned to the student, one for them to check and the ones without answers to see if the student really understands. The main weakness of the text seems to be not showing the specific work (units crossed out, etc) for numerical problems (unit conversions, stoichiometry problems, etc) Students really need those specific steps to help them build confidence towards attempting them themselves.

Reviewed by Nissa Garcia Ivers, Adjunct Chemistry Professor, Southwestern Oregon Community College on 1/28/22

The book is great for an introductory chemistry class - it covers all the necessary learning outcomes for my particular course. I would like to point out that perhaps for the Converting Units chapter, perhaps more examples showing explicitly how... read more

The book is great for an introductory chemistry class - it covers all the necessary learning outcomes for my particular course. I would like to point out that perhaps for the Converting Units chapter, perhaps more examples showing explicitly how units cancel would be much more helpful for instructors.

I have not so far seen any errors in this text.

The text is matter of fact, so it will withstand the test of time.

Clarity rating: 4

The book is clear and concise, however, I think that it can benefit using more visual aids/illustrations for more visual learners. The addition of visual aids can contribute to its clarity.

The book is consistent in language and style, as well as the format. It is consistent in the presence of end of chapter material, which I particularly like since it summarizes each chapter nicely.

Modularity rating: 3

It would help if this textbook was customizable, however, this is easily addressed by assigning specific chapter readings and pages to students.

I like the sequence of the book - the order is how I normally would teach an intro to chemistry class from chapters 1-6, after which I would go to chapters 9-10.

Interface rating: 3

The navigation of the online book is ok, but I wish that the table of contents would be on the side, and it can stay on display as I click through chapters. I wish there were more illustrations and more visual examples, which would really improve on this book , and show more work for the problem solving aspect, such as the stoichiometry part and calculating concentrations and converting units, in addition to mentioning the steps, which it already does.

I have not found any grammatical errors

The text is matter of fact, so I didn't see any cultural issues with this book

Reviewed by Marissa Shepherd, Instructor, Rogue Community College on 1/13/21

I felt like this book is a basic outline of a GOB course, but felt lacking in many areas. This might be appropriate if you were covering the entire book in one quarter, but not suitable for a full year GOB series. Generally the gen chem section... read more

Comprehensiveness rating: 3 see less

I felt like this book is a basic outline of a GOB course, but felt lacking in many areas. This might be appropriate if you were covering the entire book in one quarter, but not suitable for a full year GOB series. Generally the gen chem section was good, but was shockingly sparse in gas laws.

Seems accurate, but could use more examples especially of more difficult concepts.

I did like the intro stories in the beginning of each chapter which also helps relate the material, but it needs more pictures to be engaging.

Clarity rating: 3

The writing is clear, but a lack of formatting and pictures makes the textbook feel like a huge wall of text which will be difficult for students.

Consistency rating: 4

Very consistent with itself.

Modularity rating: 2

Unfortunately, this portion hurts the textbook the most. The pictures are extremely small compared to the text and very few and far between. This leaves the feeling of a huge wall of text. Formulas and chemical expressions are given in the same font as the main body which exacerbates the issue.

Organization/Structure/Flow rating: 3

Generally follows the expected "GOB" series course material. There are a few sections that are lumped together and it is lacking in the biochemistry section.

Very small images especially in the biochem section detract from the experience and make it difficult to comprehend the material.

Grammar is good

Good references!

I hope this book will be developed more. I have been searching for a good open source GOB replacement textbook, but this has been shockingly difficult to find. More engaging and better thought out visuals will help the book. It also needs more references in the back, standard tables.

Reviewed by Mary Coville, Adjunct Instructor, Lane Community College on 8/26/20

There is no glossary or index and the text could really use one. An enormous amount of material is covered, and if a student needs to review something from earlier or look up a definition, the chapter sub-headings aren’t sufficient. The book... read more

There is no glossary or index and the text could really use one. An enormous amount of material is covered, and if a student needs to review something from earlier or look up a definition, the chapter sub-headings aren’t sufficient. The book could also use a more extensive appendix that includes all the tables that normally appear inside the front and back covers of a physical textbook – table of polyatomic ions, list of common ions, conversion factors, etc. Most subjects are covered appropriately but more coverage could be given to chemical equilibrium. Also, condensation and hydrolysis reactions could be more effectively emphasized.

I found no glaring errors.

The book was written before the periodic table was filled in. Also, I would like to see an update in the next year or so that includes a description of SARS-COV-2 in the section on viruses. There is currently a description of HIV and the drugs used to treat it in the virus section, and that probably needs to be updated.

The text is written in simple language appropriate for beginning college students including English language learners.

I found no problems with consistency.

I did not like that the intro to organic compounds, including describing functional groups, occurs in chapter 4: covalent bonding. Then in chapter 12, where organic chemistry really begins in earnest, the authors refer back to chapter 4.

Other than putting the intro to organic compounds in chapter 4, the organization is good.

Interface rating: 4

Some figures were missing in the online version. My browser prevented me from accessing the PDF version. I liked that there was a choice of reading the entire chapter continuously or proceeding through it section by section.

I found no grammatical errors.

The text is not culturally insensitive or offensive, but there is little cultural diversity in the examples. The main text focuses on the science. Inset “career focus” boxes use gender neutral pronouns, although for “genetics counselor” a photograph is included where the counselor is a white woman and her client appears to be a woman of color. There are only a few depictions of people and they are of dead white scientists: Linus Pauling, John Dalton, William Morton (dentist to first use diethyl ether as a general anesthetic).

Reviewed by Danna Sharp, Lecturer, Shenandoah University on 6/18/20

This is a standard text for a course intended as an introduction to chemistry, organic, and biochemistry for non-majors. I do feel it could be improved by additional figures and images to explain concepts. It definitely lacked in this. A few... read more

This is a standard text for a course intended as an introduction to chemistry, organic, and biochemistry for non-majors. I do feel it could be improved by additional figures and images to explain concepts. It definitely lacked in this.

A few things I noticed: -the text does not teach students how to draw covalently bonded lewis structures (it does teach ionic) -drug kinetics are not mentioned in the organic/biochem section -quantum description of atoms does not explain the electron jump in the d orbitals -no arrow pushing is used in the organic section and students are required to memorize reactants and products instead

However, all of these things may be fine depending on the course. Other than the omission of lewis structures, I found this text adequate but high on the memorization requirements in the organic and biochem sections.

The book was accurate. Most of the issues I felt came from issues of omission. This happened by not going into more depth on explanations of topics to help improve student comprehension instead of focusing on memorization based learning.

This again may be fine depending on your course.

I liked the examples relating chemistry to the real world at the beginning of each chapter often having a medical focus. As many students who take courses like this are in medical related fields, I find it very helpful.

This book reads like a dense workbook. It has very good definitions of terms and lots of practice problems with solutions, however, it lacks images and figures to help describe concepts and ideas. So if your students need a lot of practice problems, and your class is supplemented with a lecture with lots of images to help the students visualize concepts, this would be an ideal text. It is also intended for non-majors.

Book was very consistent and easy to locate content. A lot of problems are included in the text and nearly all had solutions. So it provides a lot of practice for students.

The text was very easy to read. It was also very concise which I appreciated. Very good definitions!

Organization/Structure/Flow rating: 4

I felt this text was very well organized. Everything was where it was supposed to be and the material covered is standard for what is expected in a non-majors course.

The text had no interface issues I noticed.

No Grammatical Errors that I saw. Sometimes it would gloss over or skip more complex explanations of topics.

The text was not culturally insensitive in any way.

In summary, this is a standard text for a course intended as an introduction to chemistry, organic, and biochemistry for non-majors. I do feel it could be improved by additional figures and images to explain concepts. It definitely lacked in this.

I would also appreciate a lessened focus on memorization in the organic and biochemistry portions (personal preference). Nearly all practice questions and topics were based on memorization. The reason as to why certain chemical and biochemical reactions happen was not included. There was a good focus on applications in the organic and biochemistry sections however.

In my opinion, the best parts of the text were how concise and clear the definitions were and how all of the problems had solutions for the students to check their work with.

Reviewed by Soumya Bhattacharya, Assistant professor, University of Providence on 2/28/20

The book is quite comprehensive. Given that this course can be either 2 semesters (16 week each) or 1 semester (8 weeks each module General + Organic &amp; Biochemistry), the book is detailed enough in materials presented to be adapted for an... read more

The book is quite comprehensive. Given that this course can be either 2 semesters (16 week each) or 1 semester (8 weeks each module General + Organic & Biochemistry), the book is detailed enough in materials presented to be adapted for an abridged, more focused direction.

The informations are accurate and concise for the course the book is intended for.

The health science references were well placed. Given that the majority of the readers of this kind of textbook will be allied health science majors, the examples and extrapolations are quite relevant.

The language is simple and lucid. The technical terms are both defined and explained with adequate examples.

The organization of the chapters are pretty standard. For this kind of a textbook, atoms first approach suits better and that is how exactly the book is laid out.

Interface rating: 2

The formatting requires a lot of work. The figure headings and the actual figures must be in the same page. The subheadings or the headings with their accompanying texts should have been tried to be kept in one page, wherever possible. This book should have been under the scanner of a compositor for much better visual appeal. Use or certain colors (like orange) was a disaster. It actually distracted the reader and made it harder to focus. The organization will tremendously enhance the learning and teaching experiences.

Grammatical Errors rating: 4

Cultural Relevance rating: 4

Reviewed by Chandra Kunapareddy Ph.D., Assistant Professor of Chemistry, Blue Mountain Community College on 1/6/20

As the authors stated in the preface of this book, this book is ideal for the survey of the GOB chemistry full semester course. However considering I teach at an institution that teaches in quarters semester instead of a full semester, I need to... read more

As the authors stated in the preface of this book, this book is ideal for the survey of the GOB chemistry full semester course. However considering I teach at an institution that teaches in quarters semester instead of a full semester, I need to cut down on a couple of chapters and topics from this book to make it appropriate for my students. I do want to use this book for single quarters to teach general, organic and biological chemistry in separate quarters. I find that the general chemistry component is very comprehensive to teach in the one-quarter semester. However, the book went lighter in content for organic and biological chemistry. Which makes me need to look for supplemental content to make up for the needed content for the quarter semester for each of organic and biological section. I find that this book uses much fewer images than a regular textbook. It would be great if this book can add more images throughout the book to keep a student engaged.

I used this book for the introductory general chemistry one quarter and covered chapters from 1 to 11. I didn't find any inaccuracies with the text in these first 11 chapters. I also adopted this book for the survey of GOB chemistry class with selected topics and I find no issues so far.

This book does a good job of covering necessary basic topics to introduce chemistry for non-majors students. However, many of my students are non-chemistry majors and they always look for justification to learn any new chemistry concept. The book will look much more relevant for students if it includes a few more health-related applications for the major concepts.

This follows a pattern similar to any GOB textbook available in the market. So, it does have good clarity of chapters' progressions and the content discussed under each chapter.

The book is consistent in its style of presenting information in each chapter. Each chapter starts with an opening essay, followed by sub-sections that discusses that covers parts of the chapters in a progressive manner.

I like how this simplifies each topic by consistently presenting learning objectives, concept review exercises, answers, key takeaways, more examples, and answers before moving on to another topic in the same chapter.

No problems here. As I previously mentioned in the modularity section, the book is very organized and very easy to find the information especially if you use an online textbook. For my online chemistry class, I copy and paste the link of the specific chapters on the canvas shell page for my students to directly access it online.

I commend the author's effort to put together this book available in OpenStax mode. However, this book could use some formating help to make it more attractive for aspiring users. For example, it is uncommon for a textbook to left indent through the book instead of adjusting the sides. The book at times has less clarity element symbol. For example, for example, 5 on page 107 of the textbook has given mass and atomic number information of the elements Cl, I and other elements. The authors try to paste an image instead of using MS word to present this information, which leads to blurry images of the elements. It is still readable but it feels low clarity. I have observed these types of similar issues when the textbook presents problem-solving equations using conversion factors.

There are no obvious grammatical errors. The students in my class liked the way the book is written as it is very easy for them to read. For a professor who used publisher books in the previous years, this book might seem a little informal in writing. However, it doesn't bother me much, because as I won't require to read this as thoroughly as students since I am already familiar with the content over the years.

No issues here.

I commend the effort put in by the author to make this book available for free. Thank you on behalf of all the students who are using this book.

Reviewed by Adam Wenz, Associate Professor of Chemistry, Flathead Valley Community College & TRAILS on 11/27/19

The coverage of general chemistry topics in this text is very good considering the level of course for which this is intended. However, I feel that there are a couple of areas that could use improvement: The discussion of nuclear chemistry in... read more

The coverage of general chemistry topics in this text is very good considering the level of course for which this is intended. However, I feel that there are a couple of areas that could use improvement:

The discussion of nuclear chemistry in Chapter 11 does not cover electron capture, or positron emission. Not all texts of this type cover this information, but I feel it would be useful to do so.

Chemical equilibrium is minimally discussed, with no mention of Le Chatelier’s principle. There is no mention of chemical kinetics. I would prefer a basic chemistry textbook to at least cover these topics in a qualitative fashion, if nothing more.

Coverage of organic chemistry and biochemistry topics is very good, and is similar in scope to other GOB textbooks. I don’t have any suggestions for improvement on these topics.

On page 866, there is a discussion of D- vs. L- forms of carbohydrates; the structure of L-(-)-glyceraldehyde appears to have an error.

Few, if any, other errors were noted. Most other errors are likely artifacts from conversion to pdf format, as they involved mainly formatting issues in equations.

The content of a chemistry text at this level is unlikely to see drastic changes over time, with the exception of newer techniques and technologies seen in biochemistry. As such, I feel this book would not need updates very often.

Perhaps the periodic table given at the end of the text could be updated to be current. Based upon the information given, it appears to date from the late 2000’s.

The text is written very well. Topics are presented in a clear fashion. The text is written at a level appropriate for the intended audience. Flowcharts, photos, and figures are well-designed in general. Some tables (e.g. the amino acids table) could use reformatting for better clarity of the information contained therein.

Chapters are written and organized in a very consistent manner. Terminology is up to date and used consistently throughout the text.

Each chapter is broken up into sections, followed by a series of practice exercises. Some readers may find this distracting and choppy, but it is a matter of preference.

The chapters are organized in the order typically found in GOB type textbooks, which is just fine.

In-text exercises and end-of-chapter questions have the answers given immediately afterwards. I suggest moving the answers to another portion of the book (perhaps an appendix). This would improve student learning, in my opinion.

The pdf version of this book does not include a table of contents, nor does it include an index. This makes navigation to a particular topic more difficult unless you happen to know which chapter contains the desired material beforehand.

When the book was converted from online to pdf format, the embedded links within the text remain blue in color, suggesting that the links are still active. However, those links are all inactive. This could be remedied in a number of ways.

Other links are embedded in the text (such as those on page 479), and they are active. However, the links might need to be updated, as the material on those webpages does not fit with the context of where they are in the book itself.

Figures and tables, in general, seem to have retained their proper formatting during the conversion to pdf. They seem to be well thought out and convey their information well.

Mathematical formulas (such as those showing conversion factors) are not always consistently formatted…they appear as though they have been copied from one place to another, and appear blurry as a result. This may be an artifact of the conversion to pdf format.

I did not run across any errors in grammar.

I did not see any issues here.

Please note that this review is of the PDF version of this textbook. The online version of this text may not have as many formatting issues. Even though this text is listed as being intended for a one-semester GOB course, I feel it could also be modified for use in a two-semester GOB sequence. The first semester could cover the general chemistry topics, followed by the second semester being half organic chemistry and half biochemistry. This book should serve the intended audience well.

Reviewed by Andrew Bonham, Professor, Metropolitan State University of Denver on 7/16/19

This textbook addresses all the major topics that I would expect to see in a General, Organic, and biological Chemistry textbook. It could benefit from added material in the following areas: chemical reaction rates, organic molecule chirality,... read more

This textbook addresses all the major topics that I would expect to see in a General, Organic, and biological Chemistry textbook. It could benefit from added material in the following areas: chemical reaction rates, organic molecule chirality, and nutrition. The topic coverage compares favorably to other common textbooks used for these courses.

The content is very accurate, with very few errors in its treatment of the subject. More specifically, the content review exercises included with each section are salient and accurate, sometimes giving important context to the material that preceded them.

Relevance/Longevity rating: 3

Many chemical concepts are timeless, but particularly in biochemistry, the pace of advancement is very high. Some of the material related to biochemistry is already dated and should be updated with more modern techniques and examples. To be clear, nothing is inaccurate-- it’s simply not the ‘state of the art’ anymore, and it’s better to expose students to more up-to-date information. Particularly given that this textbook will be used in pre healthcare-focused careers, it’s important to supplement the text with examples of techniques that students are likely to encounter in their future careers.

This textbook does an excellent job of using short, direct language to express important concepts, avoiding jargon and speaking at the appropriate level for its audience. This is one of the great strengths of this textbook.

It is clear that this textbook originally had one author; it is very consistent and clear in its terminology and tone throughout.

This textbook is extremely modular and self-contained; each section stands on its own with internal introductions, concept reviews, exercises, and summaries. You could take any chapter and use it independently or interweave it with other resources.

This textbook follows a very common organizational pattern for General, Organic, and Biological Chemistry textbooks, making it easy to adapt for instructors used to other resources. Within each chapter, topics are presented in a logical manner and build appropriately in complexity.

The web interface of the book is clear, well-organized, and accessible. The PDF version has topics span pages without clear breaks for different topics at times, and could use effort at better interactive hyperlinking.

The text has some noticeable typos and formatting errors, but very few hinder comprehension. Core concepts are clearly presented, and the English style and tone is appropriate.

I did not observe any topics or discussions in the book that would be considered culturally offensive. For instance, its discussion of genetic diseases was very respectful.

This textbook is comprehensive and correct, but barebones. A concerted effort to add 3 to 5 additional exercises and challenge problems to each section of the book would be worthwhile and dramatically increase its impact.

Reviewed by Pratikkumar Rathod, Assistant Professor, LAGCC on 5/17/19

This GOB book is well-written for non-majors who required to learn basic chemistry in a semester. The topics in the book are adequately described without going into much details. The text provides good numbers of exercises relating to real-world... read more

This GOB book is well-written for non-majors who required to learn basic chemistry in a semester. The topics in the book are adequately described without going into much details. The text provides good numbers of exercises relating to real-world problems which I think is beneficial to the students to understand the relevance of the topics. The introduction of opening essays in the beginning of chapters is a great way to connect the relevance of the information in the chapters with real problems. There is no index or glossary.

Content Accuracy rating: 4

The content and the information provided in the book are accurate. However, I find quite a few space errors in the text, especially on page #141 (chapter summary section of Chapter-2). Besides answers of the exercise on the page #207 (problems- 5, 7, 9, 11) does not match with questions.

The chemistry content in this book should remain relevant for long period of time. It includes up to date information.

The book is written in an accessible way by keeping non-majors chemistry students in the mind. All terms are well-defined and explained in simple (yet scientific) language.

Each chapter in the book does follow a consistent pattern including Learning objectives, examples, skill-building exercises, concept review exercises and key takeaways. The text, font and language used throughout the book is uniform.

The sections and information provided in the book can easily be divided (into subsections or reading assignment) depending on course requirement.

The chapters in the book are written in well-organized and consistent manner. The flow of chapters in the book is logical.

The PDF version of the book offers poor interface. The lack of clickable links for tables and figures is the biggest negative. The resolution of formulas in the text as well as in the problems can be better.

The book has quite a few typos and space errors but not a major issue.

I did not find anything that might be considered as culturally offensive in the book.

Reviewed by Gregory Cornell, Adjunct Instructor, Southern University on 4/30/19

This GOB text delivers in providing just what the title denotes. In this era of having to cram two semesters of material into a one semester course, the text adequately provides basic level content. The text lacks an index and glossary. read more

This GOB text delivers in providing just what the title denotes. In this era of having to cram two semesters of material into a one semester course, the text adequately provides basic level content. The text lacks an index and glossary.

The text appears to be mostly accurate with minimal detection of errors.

In the last 13 years, I have had to utilize several GOB texts, as well as textbook written for non-science majors. I would definitely attest to its relevance. Some instructors might like to see more information provided in key areas, but overall, it follows the norm in up to date content.

I find this GOB text to be clear with concise step by step examples for students to follow.

This text shows consistency throughout in its progression of terms and concepts.

The text is presented clearly and concise in "bite-size chunks". Students are often intimidated by the subject name as well as the content. These compartmentalized smaller reading sections help students to master concepts before moving on to others too fast.

The organization of the topics in this text were mostly standard.

There were no distortion of images or confusing displays during the review of this text. The navigation capabilities are limited to scrolling only.

There were only a few grammatical errors detected during my review.

Cultural Relevance rating: 3

There were no cultural sensitivity issues detected during my review of this text, based on the lack of cultural material provided.

Reviewed by Kinesha Harris, Assistant Professor, Southern University on 4/29/19

The textbook provides adequate coverage of the topics that would be discussed in a one or two-semester introductory chemistry course for health science or other non-science majors. It presents topics with an appropriate level of discussion and... read more

The textbook provides adequate coverage of the topics that would be discussed in a one or two-semester introductory chemistry course for health science or other non-science majors. It presents topics with an appropriate level of discussion and provides real-world links to the topics discussed to make the material relevant to students. There is no glossary or index; however, there are bold-face terms throughout the text, which show definitions as screen tips.

The content reviewed in the textbook is accurate, error-free and unbiased.

The textbook contains up to date information and provides examples and additional information that cover scientific advances from the last decade.

The text is written in plain language, with content specific language as necessary. New technical or scientific terms are defined within the text as presented.

The textbook is consistent in layout and levels of content from chapter to chapter.

The content is divided into sections within each chapter, which facilitates reading and comprehending the material. Students can be assigned individual sections or groups of sections to read rather than the entire chapter at once. There are pre- and post-checks for each section and the sections reference appropriate material in other sections and chapters. However, the material easily can be reorganized if necessary.

The topics in the textbook are arranged in a logical manner, albeit slightly deviated from the common presentation of general chemistry topics, but pleasantly so. I believe the chosen organization groups all of the related materials and orders them in such a way as to allow the students to get a full understanding of the basic concepts and how they apply across the various types of matter.

There is an unusually high occurrence of broken or missing links to figures and other sections or chapters. There are missing figures and incorrectly placed figure labels. Additionally, the screen tips for the bold-face terms throughout the text show up at the top of the screen (beginning of chapter), instead of within the bounds of the paragraph where the term is located, and are usually out of screen view if you are anywhere beyond the first screen worth of text and graphics. These issues do not, however, take away from the presentation of the material as far as student understanding.

I did not notice any grammatical errors in the reviewed material.

There are no issues of cultural insensitivity or offensiveness with the textbook.

The textbook provides a good overview of general, organic and biological chemistry. It is not in-depth, but it provides enough information for an introduction to each of these areas of chemistry. I think the arrangement of the topics is beneficial and would be interested to know if students respond better to this presentation of material. The chapters could use a larger selection of problems in the End of Chapter Additional Exercises section and there are some interface issues; however, overall, I think this is a good book for general, organic and biochemistry courses.

Reviewed by Joachim Bowles, Part-time Instructor - Chemistry, Lane Community College on 12/17/18

Has more depth than necessary for my survey course when it comes to general chemistry and adequately covers organic and biochemistry topics. read more

Has more depth than necessary for my survey course when it comes to general chemistry and adequately covers organic and biochemistry topics.

No errors noticed.

While the understanding of the minute details of biochemistry are often changing, this book does a good job of keeping more of an overview on these topics to maintain relevance.

The overall tone is accessible, but it would be nice if there were more sections/examples that demonstrated the topics being applied to real world problems.

Formatting and tone remain consistent throughout the book.

Topics are broken into logical chapters, which in turn have numbered sections. Some of these chapter sections can run long, so having a method to break them up further could be useful.

Builds from gen chem topics to organic and finally to biochem.

Distortion on images for chemical equations and molecular structures. Its not book breaking, but some of these are quite fuzzy.

No grammatical errors noticed.

Overall applications/examples lacking, which carries over to inclusivity as well.

Overall the book presents the topics I need for my course, but the presentation is somewhat bare bones as there could be more of an emphasis on applications (and maybe some historical context for topics like atomic structure). Also, visually some improvements could be made as the figures are often blurry and there's a periodic table at the end that is oddly formatted across two pages.

Reviewed by Lisa Sharpe Elles, Assistant Teaching Professor, University of Kansas on 12/15/18

This textbook is a great one-semester overview of general, organic, and biochemistry for students needing an introduction to chemistry, such as pre-nursing or exercise science students. There is enough information for students to get a good, basic... read more

This textbook is a great one-semester overview of general, organic, and biochemistry for students needing an introduction to chemistry, such as pre-nursing or exercise science students. There is enough information for students to get a good, basic foundation to chemistry in a short period of time without getting bogged down in too many details. There is no stand alone index or glossary but within the text there are definitions of bolded and underlined words if you hover over them with the mouse.

There are no errors other than occasional missed spaces throughout the pdf version. A minor annoyance is that the colors of the nucleus and electrons switch between chapter 2 and 4, which could be confusing to students that pay attention to details.

For the most part, this book is relevant and up-to-date. This chemistry content in this textbook is straightforward and presented in a very practical order that can be adapted (added to) easily when updates become necessary. However, some of the connections to health and chapter introductions will need updates over time to keep up with changes in the health professions. The organic naming section still uses the older nomenclature however, this is common among all equivalent print GOB textbooks. One out-of-date item is the food pyramid in the last section of chapter 4. This link should be changed to the new guidelines.

The text is very practical, clear, and concise, and definitely written with the specific audience in mind. Difficult concepts and topics are broken down in a way that makes sense without losing the relevant connections for understanding chemistry.

Terminology and is consistent throughout. Each chapter begins with an introduction to the content and ends with a summary of material to review. Each section begins with clear learning objectives and ends with examples, key takeaways, and practice questions with some answers.

Within this textbook the chapter content is divided nicely into sections that are the appropriate length and easy to read. Within each section, there are links to other content in the book. This allows for sections to stand alone, making reorganization into any order easy.

The organization of content is appropriate and fitting for a one-semester GOB textbook. The flow of content works well and there are no unnecessary figures interrupting the text. Nuclear chemistry felt a little out of place but it is a chapter that doesn't quite fit in anywhere logically although it fits a little better within the introduction to the structure of atoms. It would be nice to see more connections to VSEPR and lewis structures in the organic chemistry chapter. It is a good place to review content learned earlier. In addition, there should be a periodic table presented much earlier on and not just in the appendix. It would be really easy to link to any website that has an updated table that students can interact with and learn from.

The pdf version had a lot of spacing issues and distorted figures but this did not seem to be an issue in the online version. Additionally, the format for superscripts on ion symbols was odd in some places, which is a little distracting but should not be confusing. It would be nice to be able to click on figures and zoom in to them separately from the text.

There were no grammatical errors noticed.

This book is not offensive or culturally insensitive.

This textbook is definitely designed with the audience in mind, which is much appreciated. Many of the notes and brief descriptions perfectly and clearly break down concepts in a way that is easy for beginning chemistry students to figure out and learn from. In addition, the summary sections at the end of each chapter is very useful and gives students a place to summarize chapter content but also somewhere to start reviewing for exams.

Reviewed by Stan Svojanovsky, Assistant Professor, Missouri Western State University on 5/21/18

This book is very comprehensive and covers the basics of GOB Chemistry for one or two semesters GOB course. The material is feasible for students without and prerequisite knowledge of the subject but students who are already familiar with the... read more

This book is very comprehensive and covers the basics of GOB Chemistry for one or two semesters GOB course. The material is feasible for students without and prerequisite knowledge of the subject but students who are already familiar with the basic parts of GOB Chemistry can also benefit from this textbook. The authors added multiple high quality activities (such as audio-video resources, checklists, MCQs) that make the material more interesting and reinforce the learning, comprehension and understanding via critical thinking. The text also provides many examples with step-by-step solutions in order to answer 'HOW?' and 'WHY?' question and gain a solid understanding of the subject matter. The book is divided into inorganic, organic and biochemistry parts with some aspects of analytical and physical chemistry as well.

The text is accurate. However, some of the hotlinks to additional material do not work and need to be updated.

The material is written in a long-lasting way, i.e. the main scientific information will not change very fast. Some links need to be updated but it should be relatively easy with the online textbook format. Relevance of the material with biomedical research and human health is a nice addition to the text.

The textbook is well written, the material is clear and well explained. Applications of multiple graphs and diagrams add to clarify the concepts. The great advantage of this material is the writing style using the basic vocabulary and informal style. Also 'End-of-Chapter Material' is written in a 'Study Guide' style.

The textbook is very consistent in uniform writing style, presentation of the material and interface as well. Each chapter is presented in the same order (i.e. Opening Essay, Learning Objectives, Examples, skill-building Exercises with the solution, concept review Exercises, Key Takeaway). Also, all important vocabulary is presented in bolded style.

The textbook layout is modular with each chapter divided into smaller but complete sub-chapters, clearly separated by topics and activities. All subtitles are uniform through the text and clearly labeled. The length and depth of each subsection is consistent, creating a relative easy online reading, however the navigation to each section might be more difficult for some students to move around in the text.

The textbook is organized in a typical format with initial more general topics, followed by organic and then biochemistry relevant topics. The final chapter provides the connections between previous parts as the book overview.

The layout and a PDF text format is accessible via multiple browsers and operating systems. But based on the font size some of the references posted on the bottom of the page are located differently since some parts are divided by page-beaks.

There are virtually no grammatical errors in the text. I found only a few typos that could be easily corrected.

The text is not culturally insensitive or offensive at all. However, it is focused on US students using typical US culture that might be foreign to students outside US.

This book is an excellent addition to existing Open Education Resources (OER) with a high-quality supplements for instructors, such as Instructor Manual, PPT Lecture Notes, Solution Manual, and TestBank Import for any LMS. I highly recommend it.

Reviewed by Jill Shirokawa, Visiting Assistant Professor, University of Cincinnati Clermont College on 3/27/18

This textbook includes all of the essential content needed for a one-semester General, Organic, and Biological Chemistry course. Each of the twenty chapters is divided into concept sections containing learning objectives, examples, skill-building... read more

This textbook includes all of the essential content needed for a one-semester General, Organic, and Biological Chemistry course. Each of the twenty chapters is divided into concept sections containing learning objectives, examples, skill-building exercises, concept review exercises, and answers. In addition, each chapter includes appealing features such as the Opening Essay, To Your Health, and Looking Closer that help students make connections with the chemical concepts presented. Although the subject matter is well presented, items such as a table of contents, glossary, and index are absent in this textbook.

The material in the text is accurate, however, some typos exist. Periodically, throughout the text, a reference is made to a figure, but a non-working hyperlink is provided instead.

The chemistry content within the textbook should remain appropriate for a long period of time. The information in the chapter Opening Essays help the students see the relevance of the chemical concepts. Just a few items may need updating. For example, the Opening Essay for chapter 16 contains diabetes statistics that are outdated and the MyPyramid food guidance system in chapter 4 has been replaced by the MyPlate food guidance system.

The chemical concepts are clearly written and are at an appropriate level for GOB students.

The framework of the sections within each chapter remains consistent throughout the textbook. Each section contains learning objective(s), skill building exercises, concept reviews, end of section exercises, and answers. In addition, each chapter consistently contains features such as the Opening Essay, To Your Health, and Looking Closer, which makes the chapter more appealing for students.

The modularity of the textbook is excellent. The chapters can be easily rearranged to enable a different presentation order of the material if necessary. Every chapter is divided into concept sections with every section containing learning objective(s), exercises, and answers. Having the answers attached to each section is more convenient than consistently referring to the end of the chapter or the end of the textbook.

The overall organization of the chapters and the sections within the textbook is very good. There is a logical flow from the foundational material through to the more complex material.

Due to the PDF format, the biggest interface issue is the poor maneuverability around the textbook. The need to scroll and the lack of table contents makes it difficult to navigate within the textbook. A linked access to the table of contents would be helpful. I found the inclusion of non-working hyperlinks as references to be a bit disruptive to the flow of material within a sentence. In addition, a few images are too small and many images are blurry (although readable).

I found no grammatical errors within the text.

I did not find the text to be culturally insensitive or offensive in any way. However, the text lacked photos which could serve as a means to include a variety of races, ethnicities, backgrounds, and different genders.

In general, I found the textbook to be an enjoyable read and I feel that it is written at a very appropriate level for GOB students. I liked that the learning objectives are boldly presented at the beginning of each section. Each section is well written and interesting (due to the inclusion of health and consumer information). My suggestions for improvement are: to use more diagrams and figures; to include photos to make the text more visually appealing; and to use more bold subheadings to highlight and draw attention to concepts.

Reviewed by David Merkler, Professor, University of South Florida on 3/27/18

The text is appropriate comprehensive, covering all the important concepts for the students enrolled in a GOB course. In addition, the text includes topics of biomedical relevance in an attempt to keep the students interested in the topics... read more

The text is appropriate comprehensive, covering all the important concepts for the students enrolled in a GOB course. In addition, the text includes topics of biomedical relevance in an attempt to keep the students interested in the topics covered in a GOB course.

Accuracy is fine. No glaring errors were detected - not uncommon for a GOB textbook since GOB courses cover basic topics in general chemistry, organic chemistry, and biochemistry that have been around for long time.

Relevance and longevity for a GOB textbook are hard to gauge since much of the textbook covers very basic concepts that are not likely to change or "modernize". In this text, chapters 1-10 and 12-15 are going to be largely the same in 20 years and were largely the same 20 years ago. Now, chapters 11 and chapters 16-20 could be updated (upon occasion) resulting from new discoveries in biomedical science. This reviewer would guess that the chapters covering carbohydrates (chapter 16), nucleic acids (chapter 19), and energy metabolism (chapter 20) might (emphasize might) see important changes in the next 20 years. Having said that, the basic concepts in these chapters will not change much over a 5-ish year period and any changes would be significant. Longevity for a GOB textbook is more related to issues like the long term survival of GOB courses (some universities are phasing out a GOB courses) and expectations of the students and faculty from textbooks. In particular, students seem to expect textbooks to be increasing "user friendly" as defined by the students and this expectation will change more rapidly than the materials covered in the chapters. This text could become "unpopular" for stylistic reasons far more quickly than anything related to the scientific concepts covered in the individual chapters.

Well written and quite clear. The authors have tried very hard to keep in mind the student audience for a GOB course.

Consistency is quite good. Again, the authors have kept the student audience in mind and kept terminology consistent. As anyone who has taught a GOB course knows, it is very easy to confuse this cohort of students with terminology. The authors of this text have done an excellent job, as well as possible, to eliminate this source of confusion with consistent terminology.

Outstanding for this text. The authors have done a very nice job of dividing the chapters into smaller modules to ease the students through this material. One challenge for a GOB course is the breadth of material covered and one way to handle this problem is modules. The authors have done a good job dividing the chapters into appropriate modules.

Organization is fine, except for the chapter on nuclear chemistry (chapter 11). To be honest, this is a difficult chapter to place "right" in a GOB course and making chapter 11 the nuclear chemistry chapter is fine. If I were an author, I probably would have placed the chapter right before the carbohydrate chapter, after the students have finished their "path" through organic chemistry. I would try to use the nuclear chemistry chapter to remind the students of some key concepts out of the earlier general chemistry chapters and used the nuclear chemistry chapter to try and get the students excited about the biochemical chapters - the use of 14C (and maybe 3H and 32P) in metabolic studies and the use of various isotopes for biomedical imaging. Also, biochemists use deuterium and 13c a lot in modern biomedical research. Many GOB students assume that all isotopes are radioactive and an instructor can remind the students that all isotopes are not radioactive by discussing 2H, 13C, or 18O in some biochemical context. Table 11.5 is an attempt to link isotopes to biomedical uses - why I would have placed the nuclear chemistry chapter right before the initiation of the biochemical section of the text.

I deteced no significant interface problems in going through the chapters.

I detected no grammatical errors in the text, but, to be honest, I did not read every single page with sufficient care to guarantee that the book is completely free of grammatical errors.

Cultural relevance is about as good as can be expected for a GOB text. The earlier chapters covering the basics of general and organic chemistry are the same throughout the world and, thus, are hard to place in "cultural" context.

If I taught a GOB course, I would give this text serious consideration for use - especially given the fact that my students would be able to use this text without cost (or a minimal cost, if they chose to have a printed copy).

Reviewed by Andrew Tangonan, Assistant Professor, Ohio University on 2/1/18

With the growing popularity of a one-semester GOB courses in a lot of academic institutions, this introductory book meets all the necessary requirements intended for that course. The information is presented and organized very well. However, this... read more

With the growing popularity of a one-semester GOB courses in a lot of academic institutions, this introductory book meets all the necessary requirements intended for that course. The information is presented and organized very well. However, this book has some room for improved navigation within the text.

I find the contents of this book accurate and unbiased.

This book should stay relevant for a good number of years; the core content is presented in a very straightforward manner and I don’t see it becoming obsolete any time soon. The chapters and the way it was organized and presented should be very accessible to future updates if necessary.

The book is written with significant consideration for its potential readers. As an introductory book the topics are clearly presented at a level that is easy to follow throughout the chapter. The learning outcomes are presented early on with a good end of chapter follow-ups.

The text and terminologies are consistent throughout the book. Each chapter follows the same format that should help the reader learn the content as the authors intended.

This book has 20 chapters designed as a one-semester GOB; that is a lot of topics to discuss with good depth. However, this book has a very good flow (chapters) that you can easily select and tailor topics you wish to highlight or skip. The well-organized sub-chapters with their specific learning outcomes make reorganization even easier.

The topics are presented well and the content is comparable to most GOB books currently available. They are logical and continuously build from the previous chapter. However, the readability can be improved by fixing the spacing of figures and tables (e.g. a number of figure titles are separated from the actual figure by a page).

The pdf copy I evaluated only offers “scrolling” as a means of navigating the book. I would be helpful for most readers if some links were included to a referred text, figure, appendix, or even a table of contents, which this book lacks. A table of contents with active links and link-back would also improve navigation in general.

There are no obvious grammatical errors.

I did not find anything in the book the might be considered culturally insensitive or offensive in any way.

This book warrants consideration if you are looking for a free textbook for a one semester GOB course.

Reviewed by Jeffrey Vargason, Associate Professor, George Fox University on 8/15/17

GOB (General, Organic, and Biological Chemistry) is traditionally taught as either a one-semester or a two-semester format. Based on the preface, this particular book was specifically written for a one-semester course. This book does a good job... read more

GOB (General, Organic, and Biological Chemistry) is traditionally taught as either a one-semester or a two-semester format. Based on the preface, this particular book was specifically written for a one-semester course. This book does a good job covering the subject of GOB; however, the subjects presented are covered at a sufficient depth for either a one-semester or two-semester course. There was no table of contents, index, or glossary (clickable or otherwise) in the PDF that I downloaded from the Open Textbook Library and reviewed. This created a lot of work when navigating within the textbook. There is a section at the end of each chapter devoted to summarizing the chapter including the keywords.

Overall, the content is fairly accurate. There are a few errors in figure designations in the text. For example, there is a reference to Figure 1.2 that details the steps of the scientific method in section 1.2 under “Elements and Compounds”. Either this was an intentional placeholder for the addition of a different figure that describes “Elements or Compounds” rather than the scientific method or this is an error in the placement of this reference. In addition, in the PDF that I downloaded and reviewed, there is a reference in section 1.5 to a hyperlink rather than text stating “Figure 1.7 Measuring an Object to the Correct Number of Digits”. In addition to section 1.5, this type of reference to a hyperlink rather than a title is also found in sections 1.6, 4.6, 9.1, 10.1, 10.3, 10.4, 10.5, 13.2, 13.5, 18.1, 18.2, 18.3, 18.4, 18.5, 18.6, 18.7, and 18.8. Finally, in Figure 8.4 there is a filled-wedge connecting H and F in hydrogen fluoride. This may be confusing for students especially since the figure is used to describe polar covalent bonds rather than geometry. The wedges are used in the subsequent figure (8.5) to represent geometry.

The core chemistry content in GOB at this particular level should be relevant for a substantial period of time. There are a few instances where there is some obsolescence. For example, in section 4.6 in the “To Your Health” section there is a reference to the Food Pyramid or MyPyramid. This was replaced by MyPlate in 2011, so this content is about 6 years old at the time of this review. However, it would be relatively easy to update this particular section and/or figure.

Clarity rating: 2

The text was accessible and provided adequate context to help with understanding the chemical terminology.

This textbook had a consistent set of terminology and framework with just a few exceptions that I could find. In chapter 12, there is a reference preceding Figure 12.2 that requests the reader to recall that the VSEPR theory correctly predicts a tetrahedral shape for the methane molecule from section 4.5. Section 4.5 doesn’t talk about or show the structure or geometry of methane. If the reference were changed from methane to carbon tetrachloride or if methane were added into section 4.5, this would provide internal consistency. The naming of chapter 14 (organic compounds of oxygen) and chapter 15 (organic acids and bases and derivatives) is somewhat problematic in attempting to group related compounds. Carboxylic acids would seem to fit into either chapter, but are contained in the organics acids and bases categories for obvious reasons (i.e. oxygen containing compounds that are acids). Thiols aren’t compounds of oxygen though they are somewhat related as noted in the text and aren’t traditionally placed within the category of organic acids and bases at the level of a one-semester GOB textbook. Esters would seem to fit best in the title for chapter 14, but are traditionally placed in the chapter that contains carboxylic acids since they are related by chemical reactivity (i.e. esterification). It would seem that there could be a more consistent division of content either by using different chapter names for thee existing chapters or by adding an additional organic chemistry chapter.

The text is very modular which is a huge benefit of this text. There is ample division of chapters into sections that can be individually used, abbreviated, or discarded based on the course. While this text is meant for a one-semester course, it would be difficult to cover all of the included content in 15-weeks and achieve student proficiency in each of the sections. Of course, care must be taken not to remove keywords and topics that are referenced in a future chapter if sections are discarded.

The topics are ordered in nearly the same way as printed GOB textbooks. Some instructors prefer the introduction to organic chemistry found at the end of chapter 4 (section 4.6) in this textbook to be shifted to the beginning of chapter 12. The authors did address this placement in their preface and it does show some integration of organic into general chemistry even though that was not their focus. It would seem that this section would need to be reviewed when the students reach chapter 12 which is not a bad thing, but there is a lot of content in the book to cover in the traditional 15-week semester. The other sections that could fit within either a general or organic/biological chemistry chapter are sections 5.6 (redox in organic and biochemistry) and 7.5 (energy of biochemical reactions). If section 4.6 were moved to chapter 12, then 5.6 and 7.5 would likely need to be moved into an organic or biological chemistry chapter as well. In either case, sections 4.6, 5.6, and 7.5 in their present locations don’t present a logical disruption to the flow of the book. One additional note, the use of wedges is first used within a figure in section 4.5 and then again in section 8.4 and 8.5, but the topic of wedges isn’t explained or described until section 12.2.

The vast majority of the figures and tables were free of distortion and were high quality. I only noticed a few instances where the layout of figures or tables spans two pages. The most notable and perhaps distracting instance occurs when a table is not only split between two pages, but one of the rows of content within the table is split between two pages. In all of the instances that I noticed, the table headings are present on both pages of a split table, which certainly helps mitigate some of the distraction. I don’t think these pagination issues would be an issue in an ePUB, but the only format currently available from the Open Textbook Library is a PDF. The lack of other ebook formats is perhaps one of the biggest problems with this particular text. This type of splitting of content within a row across pages in the PDF is seen in Tables 3.4, 18.4, 18.5, and 18.6. This doesn’t seem to be about maintaining a large enough font size because the text in Figures 3.7 and 19.13 is very small. In Table 12.4, the “Condensed Structural Formula” heading is so cramped within its column that the heading is wrapped into eleven rows with a maximum of three letters from the heading in any one row. In addition, the condensed structural formulas are also wrapped within their respective rows potentially causing confusion for students. This same type of wrapping of text of single word can be seen in Table 18.2. In Table 20.1, both the text and structures are all low-resolution bitmapped images. This particular table would definitely benefit from an update. Many of the metabolism specific flow charts (Figure 20.4, 20.12, 20.14, and 20.16) would also benefit from a vector graphic based treatment since the text is hard to read when bitmapped.

There were a few typos found in the text and figures. For example, pyruvate is spelled incorrectly in Figure 20.4.

I did not notice any culturally insensitive or offensive text.

Reviewed by Sean Breslin, Professor of Chemistry, Umpqua Community College on 6/20/17

The text lives up to its stated purpose. It covers basic parts of general, organic, and biological chemistry but without much depth. It avoids frilly language and is written in a style with its audience in mind. The authors' choice of health... read more

The text lives up to its stated purpose. It covers basic parts of general, organic, and biological chemistry but without much depth. It avoids frilly language and is written in a style with its audience in mind. The authors' choice of health applications were well thought out and appropriate.

Other than a few minor typos, I couldn't find any glaring errors. Many scanned figures are blurry but still readable and correct.

The authors will likely need to update a few of the very rapidly developing "health applications" to keep it relevant. Overall, however, much of the fundamental theory is well developed and should stand the test of time.

The text's prose is very accessible to the beginning chemistry student. All terms are well-defined and are easily searchable with the control-F function.

Each chapter follows a consistent pattern and each chapter builds well on the previous section.

I'm primarily using this text in the third term of a three term intro to chemistry sequence. Our third term concentrates on organic and biochemical applications. It is very easy to assign readings that skip around the text. The mode of presenting material makes this quite easy.

The text is well organized and consistent.

Interface rating: 1

The only really disappointing part of the text is its interface. The lack of a "clickable" table of contents (or any table of contents as in my pdf version) made it laborious to skip from section to section and seems like it would be a pretty simple fix. It would be nice to add more outside hyperlinks, especially for links to better figures than those included.

Minor typos, but not frequent.

This, like many texts, could benefit from highlighting the contributions of the scientists themselves. I've found that including the humanity of the researchers often makes complex material more approachable to students. As opposed to being distracting and a "diversion", it often helps the students engage better with the material.

Overall, I'm thrilled to have found this OER. It's relatively difficult to find a text this basic and to the point with respect to organic and biochemistry. Most intro gen chem texts don't delve deeply enough into the biological side and organic/biochemical books are too in depth for the course I instruct. I'll definitely be adopting this text. Thank you, authors.

Reviewed by David Canoy, Instructor, Chemeketa Community College on 4/11/17

Assuming this book is for an entry level class of students preparing to take a human anatomy and physiology course, it is very thorough in the area of chemistry and acceptably thorough in cell biology. There is a complete glossary at the end of... read more

Assuming this book is for an entry level class of students preparing to take a human anatomy and physiology course, it is very thorough in the area of chemistry and acceptably thorough in cell biology. There is a complete glossary at the end of each relevant chapter and a complete index at the end of the book.

The accuracy is excellent and up to date. I found no errors or bias.

This book would be very useful for an instructor who wishes to introduce students to the basics of chemistry and cell biology in preparation for enrolling in a more advanced human physiology course. The topics are general enough that they are not likely to become out of date. The inclusion of historical information and descriptions of professional fields related to the topics adds to the relevance.

The logical sequence of information in this book keeps it clear for the reader. The availability of the glossary at the end of each chapter also keeps the terminology accessible and understandable.

The consistency for the most part is very good. There is a break in how chapter questions are organized between the sections on chemistry in contrast to those about biology.

Two large chapters with many subheadings are chapter 3 (general and organic chemistry combined) and chapter 7 (combining nutrition, digestion, energy, reaction rates, photosynthesis and enzymes). Within the subtopics some instructors will probably want to eliminate some details (i.e. calculating pOH, discussion of s,p,d,f orbitals or free energy).

This is a very well organized book and the topics are well connected.

This book is free of any poorly constructed images. The color and detail is excellent. The copy I examined did have a structural problem at the end of chapter 7 where the summary and review questions were repeated.

No errors found

Contributions by more women and minorities could add to the historical notes in this text.

It is always tempting to want to add more to texts we use in our classes. In this case I would have liked to see more details about cellular structure (ER and Golgi Apparatus). I would also add a section to Unit 3 on patterns of human genetics/inheritance.

Reviewed by Kenneth Friedrich, Instructor of Chemistry, Portland Community College on 12/5/16

As the title suggests this book covers the basics of GOB chemistry. It includes all the appropriate material for a one semester GOB course. The book brings in organic chemistry topics earlier than many books allowing students to see the links... read more

As the title suggests this book covers the basics of GOB chemistry. It includes all the appropriate material for a one semester GOB course. The book brings in organic chemistry topics earlier than many books allowing students to see the links between the various branches of chemistry. Roughly half the book is devoted to general chemistry and there is a large focus on metabolism at the end. A table of contents and easy method to move around in the PDF would be preferable.

In general the information in the book is accurate. There are a few typos and minor font issues as with any text.

The scientific information in the book is not dramatically changing. The contents should hold up for many years. The book does a good job of helping students understand the relevance of chemistry in their lives. Each chapter has sections that tell students about various careers in science and how the information relates to human health.

The book is well written and gets right to the important information without being wordy. It is written with beginning students in mind. It could benefit from more particle level diagrams in the general chemistry chapters to help students with the visualization of various concepts. However, I wish some of the diagrams and flow charts made for this text were in more texts.

The book is very consistent in its presentation of topics. It uses the same language throughout to help students link various topics in chemistry. Each chapter points out important terminology with bolded words. Learning objectives, examples, skill-building exercises, concept review exercises, key takeaways and exercises are all clearly labeled and presented in the same order in each chapter.

Each chapter is broken down into small bite-sized chunks of material with many practice exercises. I think students would benefit from this approach. Learning objectives, examples, skill-building exercises, concept review exercises, key takeaways and exercises are all clearly labeled and presented in the same order in each chapter. The lack of an easy way to navigate to each of the chapter sections makes it difficult to move around in the book.

The book is organized in a typical fashion for GOB chemistry books. General chemistry topics are first followed by organic chemistry topics and finally biochemistry topics. The topics in each section are covered in a logical progression.

The lack of a table of contents and an easy way to navigate to each of the chapter sections makes it difficult to move around in the book. Some sections are divided by page breaks. All chapters and sections within them are clearly labeled and color coded.

In general there are no grammatical errors. There are a few typos as with any text.

The text is not culturally insensitive or offensive.

Currently our college has a year long course for our GOB series 3 quarters). If we had a two quarter GOB I would very seriously consider adopting this book.

Reviewed by Beth Manhat, Adjunct Professor, Portland Community College on 8/21/16

This open course textbook introduces the fundamental of general chemistry (measurements, atomic structure, compounds, energy, reactions, etc), introduces structure and reactions of organic chemistry, and ends with rather substantial chapters on... read more

This open course textbook introduces the fundamental of general chemistry (measurements, atomic structure, compounds, energy, reactions, etc), introduces structure and reactions of organic chemistry, and ends with rather substantial chapters on biochemistry. My interest is with the general chemistry for a prep class. This book contains all the necessary pieces, good figures, and exercises for the purpose of a fundamental chemistry class. I wish the book had a table of contents with pages to navigate the pdf more effectively

The general chemistry information appears accurate and fundamental.

Introductory chemistry has been fundamentally unchanged. This book present conventional material in a way that can ensure it application. The types of problems are expected for the level of the writing for this book.

The figures in the early chapters (1-5) make the material more straight forward for understanding. The book had bolded words for clarity, and use adequate tone and description for this level.

The text uses the appropriate terms and tone to describe fundamental structure, bonding, and steps for quantitative relationships. I also found the step description easy to follow.

Again the use of a table of contents with page numbers would be helpful here. It is difficult to know how far to "scroll" while working blind on chapter lengths and pages. However, the authors break up the existing text well with figures, captions, and problems to solve. There are heading fr sections, color coding for problems, and obvious organization to the reader.

The flow and organization of the book is logical. The authors begin with basic general chemistry, increasing complexity through compounds, reactions, energy, and acid base solutions, before reaching organic, and biochemistry.

I found a few images to be blurry, but well used. The colored boxes for problems were helpful, but often much larger than the text of the questions. I found this to be somewhat distracting.

I did not find grammatical, spelling, or significant formatting errors.

I did not detect cultural exclusion or offense.

I appreciate the fundamental and straight-to-the-point angle of this book for any GOB class. I would greatly prefer a table of contents for easier navigation.

Reviewed by Brian Kalet, Academic Success Coordinator, Colorado State University on 1/7/16

This text is intended for a one semester general, organic, biochemistry course and as such would not be appropriate for a standalone general chemistry course, organic chemistry course or biochemistry course. There is no index or glossary. read more

This text is intended for a one semester general, organic, biochemistry course and as such would not be appropriate for a standalone general chemistry course, organic chemistry course or biochemistry course. There is no index or glossary.

The text is generally accurate. However, some typos do exist.

The content is generally up to date and updates should be easy to incorporate.

The text is very accessible and technical terms are defined appropriately.

Ionic species representation needs to be consistent.

The text is easily and readily divisible into smaller reading sections, however, having an interactive table of contents would be helpful.

The material flows in a logical sequence. However, it is difficult to jump directly to a specific chapter or figure.

Being able to jump to a specific chapter or figure would be beneficial to students.

Some typos exist.

The biological examples are useful. Figures should be numbered so they can be referenced in class.

Reviewed by Paul Laybourn, Professor, Colorado State University on 1/7/16

Overall, this textbook covers all the appropriate topics to the depth necessary for a one semester course on general, organic and biological chemistry. This textbook includes units of measurement, calculations and the mathematics background... read more

Overall, this textbook covers all the appropriate topics to the depth necessary for a one semester course on general, organic and biological chemistry. This textbook includes units of measurement, calculations and the mathematics background necessary top promote quantitative thinking without burying the student in problem sets. The only omission is Gibbs free energy. No index, bookmarks or glossary are provided.

No factual or conceptual errors in this test were noted and the topics and concepts were all presented in an unbiased manner. There are a few spaces missing between some the words.

Basic general, organic and biological chemistry are not topics that are rapidly being modified or updates with new findings each year so this textbook will remain relevant for many years. Each chapter and section begins with learning objectives and ends with example problems and exercises and the key takeaway point. Each chapter begins with descriptions of how the chapter topic relates to health and societal issues, most of which are not likely to become irrelevant in the future. The topics are well subdivided so updating any revised sections should be easily done.

The text descriptions of chemical concepts clearly written and set at the appropriate level for the intended audience. All key scientific terms are defined in place and all the writing is direct and clear with a minimum of extraneous verbiage.

This text is written and organized logically and consistently.

As mentioned previously, the textbook topics are divided between the chapters and subdivided with each chapter. It will quite easy for instructors to pick an choose topics and subtopics the wish to assign for their course. Changing the order of topic assignment should present no problems.

The textbook topics and chapters begin with a definition of science, chemistry in the context of all scientific disciplines and core chemical concepts and skills. The text then progresses through the essential general chemistry, organic chemistry and biochemical topics with a logical distribution between chapters and in an order that build progressively on previous topics.

The textbook provides no other means than scrolling through the pdf to navigate through the chapters. Clear, consistent color coding and heading are provided throughout.

The text is free of grammatical error. There are a few spaces that are missing, perhaps being lost in the generation of the pdf.

Cultural Relevance rating: 2

No culturally insensitive content was included. However, the textbook could be improved through more inclusive examples, applications and cultural relevance. For example, health disparities between U.S. ethnic groups and between countries.

This textbook is intended for a one semester survey course, perhaps for pre-nursing students, etc. In addition, I believe portions of this textbook could be assigned for background and review of core general and organic chemistry topics for students in more advanced biochemistry courses.

Table of Contents

• Chapter 1: Chemistry, Matter, and Measurement
• Chapter 2: Elements, Atoms, and the Periodic Table
• Chapter 3: Ionic Bonding and Simple Ionic Compounds
• Chapter 4: Covalent Bonding and Simple Molecular Compounds
• Chapter 5: Introduction to Chemical Reactions
• Chapter 6: Quantities in Chemical Reactions
• Chapter 7: Energy and Chemical Processes
• Chapter 8: Solids, Liquids, and Gases
• Chapter 9: Solutions
• Chapter 10: Acids and Bases
• Chapter 11: Nuclear Chemistry
• Chapter 12: Organic Chemistry: Alkanes and Halogenated Hydrocarbons
• Chapter 13: Unsaturated and Aromatic Hydrocarbons
• Chapter 14: Organic Compounds of Oxygen
• Chapter 15: Organic Acids and Bases and Some of Their Derivatives
• Chapter 16: Carbohydrates
• Chapter 17: Lipids
• Chapter 18: Amino Acids, Proteins, and Enzymes
• Chapter 19: Nucleic Acids
• Chapter 20: Energy Metabolism

Ancillary Material

About the book.

The Basics of General, Organic, and Biological Chemistry by David W. Ball, John W. Hill, and Rhonda J. Scott is for the one-semester General, Organic and Biological Chemistry course. The authors designed this textbook from the ground up to meet the needs of a one-semester course. It is 20 chapters in length and approximately 350-400 pages; just the right breadth and depth for instructors to teach and students to grasp.

In addition, The Basics of General, Organic, and Biological Chemistry is written not by one chemist, but THREE chemistry professors with specific, complimentary research and teaching areas. David W. Ball's specialty is physical chemistry, John W. Hill's is organic chemistry, and finally, Rhonda J. Scott's background is in enzyme and peptide chemistry. These three authors have the expertise to identify and present only the most important material for students to learn in the GOB Chemistry course.

These experienced authors have ensured their text has ample in-text examples, and ”Test Yourself“ questions following the examples so students can immediately check their comprehension. The end-of-chapter exercises will be paired, with one answered in the back of the text so homework can easily be assigned and self-checked.

The Basics of General, Organic, and Biological Chemistry by David W. Ball, John W. Hill, and Rhonda J. Scott is the right text for you and your students if you are looking for a GOB textbook with just the right amount of coverage without overdoing the concepts and overwhelming your students.

About the Contributors

Dr. David W. Ball is a professor of chemistry at Cleveland State University in Ohio. He earned his PhD from Rice University in Houston, Texas. His specialty is physical chemistry, which he teaches at the undergraduate and graduate levels. About 50% of his teaching is in general chemistry: chemistry for nonscience majors, GOB, and general chemistry for science and engineering majors. In addition to this text, he is the author of a math review book for general chemistry students, a physical chemistry textbook with accompanying student and instructor solutions manuals, and two books on spectroscopy (published by SPIE Press). He is coauthor of a general chemistry textbook (with Dan Reger and Scott Goode), whose third edition was published in January 2009. His publication list has over 180 items, roughly evenly distributed between research papers and articles of educational interest.

Dr. John W. Hill is professor emeritus from the University of Wisconsin–River Falls. He earned his PhD from the University of Arkansas. As an organic chemist, he has more than 50 publications in refereed journals, most of which have an educational bent. He has authored or coauthored several introductory level chemistry textbooks, all of which have gone into multiple editions. He has also presented over 60 papers at national conferences, many relating to science education. He has received several awards for outstanding teaching and has long been active in the American Chemical Society—both locally and nationally.

Dr. Rhonda J. Scott is a professor of chemistry at Southern Adventist University in Collegedale, Tennessee. She earned her PhD from the University of California at Riverside and has a background in enzyme and peptide chemistry. Previous to Southern Adventist, she taught at Loma Linda University and the University of Wisconsin–River Falls. In the past 10 years, she has made several presentations at national American Chemical Society meetings and other workshops and conferences. She has also been very active in the development of teaching materials, having reviewed or contributed to other textbooks and test banks.

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The Complete IB Extended Essay Guide: Examples, Topics, and Ideas

International Baccalaureate (IB)

IB students around the globe fear writing the Extended Essay, but it doesn't have to be a source of stress! In this article, I'll get you excited about writing your Extended Essay and provide you with the resources you need to get an A on it.

If you're reading this article, I'm going to assume you're an IB student getting ready to write your Extended Essay. If you're looking at this as a potential future IB student, I recommend reading our introductory IB articles first, including our guide to what the IB program is and our full coverage of the IB curriculum .

IB Extended Essay: Why Should You Trust My Advice?

I myself am a recipient of an IB Diploma, and I happened to receive an A on my IB Extended Essay. Don't believe me? The proof is in the IBO pudding:

If you're confused by what this report means, EE is short for Extended Essay , and English A1 is the subject that my Extended Essay topic coordinated with. In layman's terms, my IB Diploma was graded in May 2010, I wrote my Extended Essay in the English A1 category, and I received an A grade on it.

What Is the Extended Essay in the IB Diploma Programme?

The IB Extended Essay, or EE , is a mini-thesis you write under the supervision of an IB advisor (an IB teacher at your school), which counts toward your IB Diploma (learn more about the major IB Diploma requirements in our guide) . I will explain exactly how the EE affects your Diploma later in this article.

For the Extended Essay, you will choose a research question as a topic, conduct the research independently, then write an essay on your findings . The essay itself is a long one—although there's a cap of 4,000 words, most successful essays get very close to this limit.

Keep in mind that the IB requires this essay to be a "formal piece of academic writing," meaning you'll have to do outside research and cite additional sources.

The IB Extended Essay must include the following:

• A title page
• Contents page
• Introduction
• Body of the essay
• References and bibliography

Additionally, your research topic must fall into one of the six approved DP categories , or IB subject groups, which are as follows:

• Group 1: Studies in Language and Literature
• Group 2: Language Acquisition
• Group 3: Individuals and Societies
• Group 4: Sciences
• Group 5: Mathematics
• Group 6: The Arts

Once you figure out your category and have identified a potential research topic, it's time to pick your advisor, who is normally an IB teacher at your school (though you can also find one online ). This person will help direct your research, and they'll conduct the reflection sessions you'll have to do as part of your Extended Essay.

As of 2018, the IB requires a "reflection process" as part of your EE supervision process. To fulfill this requirement, you have to meet at least three times with your supervisor in what the IB calls "reflection sessions." These meetings are not only mandatory but are also part of the formal assessment of the EE and your research methods.

According to the IB, the purpose of these meetings is to "provide an opportunity for students to reflect on their engagement with the research process." Basically, these meetings give your supervisor the opportunity to offer feedback, push you to think differently, and encourage you to evaluate your research process.

The final reflection session is called the viva voce, and it's a short 10- to 15-minute interview between you and your advisor. This happens at the very end of the EE process, and it's designed to help your advisor write their report, which factors into your EE grade.

Here are the topics covered in your viva voce :

• A check on plagiarism and malpractice
• Your reflection on your project's successes and difficulties
• Your reflection on what you've learned during the EE process

Your completed Extended Essay, along with your supervisor's report, will then be sent to the IB to be graded. We'll cover the assessment criteria in just a moment.

We'll help you learn how to have those "lightbulb" moments...even on test day!  

What Should You Write About in Your IB Extended Essay?

You can technically write about anything, so long as it falls within one of the approved categories listed above.

It's best to choose a topic that matches one of the IB courses , (such as Theatre, Film, Spanish, French, Math, Biology, etc.), which shouldn't be difficult because there are so many class subjects.

Here is a range of sample topics with the attached extended essay:

• Biology: The Effect of Age and Gender on the Photoreceptor Cells in the Human Retina
• Chemistry: How Does Reflux Time Affect the Yield and Purity of Ethyl Aminobenzoate (Benzocaine), and How Effective is Recrystallisation as a Purification Technique for This Compound?
• English: An Exploration of Jane Austen's Use of the Outdoors in Emma
• Geography: The Effect of Location on the Educational Attainment of Indigenous Secondary Students in Queensland, Australia
• Math: Alhazen's Billiard Problem
• Visual Arts: Can Luc Tuymans Be Classified as a Political Painter?

You can see from how varied the topics are that you have a lot of freedom when it comes to picking a topic . So how do you pick when the options are limitless?

How to Write a Stellar IB Extended Essay: 6 Essential Tips

Below are six key tips to keep in mind as you work on your Extended Essay for the IB DP. Follow these and you're sure to get an A!

#1: Write About Something You Enjoy

You can't expect to write a compelling essay if you're not a fan of the topic on which you're writing. For example, I just love British theatre and ended up writing my Extended Essay on a revolution in post-WWII British theatre. (Yes, I'm definitely a #TheatreNerd.)

I really encourage anyone who pursues an IB Diploma to take the Extended Essay seriously. I was fortunate enough to receive a full-tuition merit scholarship to USC's School of Dramatic Arts program. In my interview for the scholarship, I spoke passionately about my Extended Essay; thus, I genuinely think my Extended Essay helped me get my scholarship.

But how do you find a topic you're passionate about? Start by thinking about which classes you enjoy the most and why . Do you like math classes because you like to solve problems? Or do you enjoy English because you like to analyze literary texts?

Keep in mind that there's no right or wrong answer when it comes to choosing your Extended Essay topic. You're not more likely to get high marks because you're writing about science, just like you're not doomed to failure because you've chosen to tackle the social sciences. The quality of what you produce—not the field you choose to research within—will determine your grade.

Once you've figured out your category, you should brainstorm more specific topics by putting pen to paper . What was your favorite chapter you learned in that class? Was it astrophysics or mechanics? What did you like about that specific chapter? Is there something you want to learn more about? I recommend spending a few hours on this type of brainstorming.

One last note: if you're truly stumped on what to research, pick a topic that will help you in your future major or career . That way you can use your Extended Essay as a talking point in your college essays (and it will prepare you for your studies to come too!).

#2: Select a Topic That Is Neither Too Broad nor Too Narrow

There's a fine line between broad and narrow. You need to write about something specific, but not so specific that you can't write 4,000 words on it.

You can't write about WWII because that would be a book's worth of material. You also don't want to write about what type of soup prisoners of war received behind enemy lines, because you probably won’t be able to come up with 4,000 words of material about it. However, you could possibly write about how the conditions in German POW camps—and the rations provided—were directly affected by the Nazis' successes and failures on the front, including the use of captured factories and prison labor in Eastern Europe to increase production. WWII military history might be a little overdone, but you get my point.

If you're really stuck trying to pinpoint a not-too-broad-or-too-narrow topic, I suggest trying to brainstorm a topic that uses a comparison. Once you begin looking through the list of sample essays below, you'll notice that many use comparisons to formulate their main arguments.

I also used a comparison in my EE, contrasting Harold Pinter's Party Time with John Osborne's Look Back in Anger in order to show a transition in British theatre. Topics with comparisons of two to three plays, books, and so on tend to be the sweet spot. You can analyze each item and then compare them with one another after doing some in-depth analysis of each individually. The ways these items compare and contrast will end up forming the thesis of your essay!

When choosing a comparative topic, the key is that the comparison should be significant. I compared two plays to illustrate the transition in British theatre, but you could compare the ways different regional dialects affect people's job prospects or how different temperatures may or may not affect the mating patterns of lightning bugs. The point here is that comparisons not only help you limit your topic, but they also help you build your argument.

Comparisons are not the only way to get a grade-A EE, though. If after brainstorming, you pick a non-comparison-based topic and are still unsure whether your topic is too broad or narrow, spend about 30 minutes doing some basic research and see how much material is out there.

If there are more than 1,000 books, articles, or documentaries out there on that exact topic, it may be too broad. But if there are only two books that have any connection to your topic, it may be too narrow. If you're still unsure, ask your advisor—it's what they're there for! Speaking of advisors...

Don't get stuck with a narrow topic!

#3: Choose an Advisor Who Is Familiar With Your Topic

If you're not certain of who you would like to be your advisor, create a list of your top three choices. Next, write down the pros and cons of each possibility (I know this sounds tedious, but it really helps!).

For example, Mr. Green is my favorite teacher and we get along really well, but he teaches English. For my EE, I want to conduct an experiment that compares the efficiency of American electric cars with foreign electric cars.

I had Ms. White a year ago. She teaches physics and enjoyed having me in her class. Unlike Mr. Green, Ms. White could help me design my experiment.

Based on my topic and what I need from my advisor, Ms. White would be a better fit for me than would Mr. Green (even though I like him a lot).

The moral of my story is this: do not just ask your favorite teacher to be your advisor . They might be a hindrance to you if they teach another subject. For example, I would not recommend asking your biology teacher to guide you in writing an English literature-based EE.

There can, of course, be exceptions to this rule. If you have a teacher who's passionate and knowledgeable about your topic (as my English teacher was about my theatre topic), you could ask that instructor. Consider all your options before you do this. There was no theatre teacher at my high school, so I couldn't find a theatre-specific advisor, but I chose the next best thing.

Before you approach a teacher to serve as your advisor, check with your high school to see what requirements they have for this process. Some IB high schools require your IB Extended Essay advisor to sign an Agreement Form , for instance.

Make sure that you ask your IB coordinator whether there is any required paperwork to fill out. If your school needs a specific form signed, bring it with you when you ask your teacher to be your EE advisor.

#4: Pick an Advisor Who Will Push You to Be Your Best

Some teachers might just take on students because they have to and aren't very passionate about reading drafts, only giving you minimal feedback. Choose a teacher who will take the time to read several drafts of your essay and give you extensive notes. I would not have gotten my A without being pushed to make my Extended Essay draft better.

Ask a teacher that you have experience with through class or an extracurricular activity. Do not ask a teacher that you have absolutely no connection to. If a teacher already knows you, that means they already know your strengths and weaknesses, so they know what to look for, where you need to improve, and how to encourage your best work.

Also, don't forget that your supervisor's assessment is part of your overall EE score . If you're meeting with someone who pushes you to do better—and you actually take their advice—they'll have more impressive things to say about you than a supervisor who doesn't know you well and isn't heavily involved in your research process.

Be aware that the IB only allows advisors to make suggestions and give constructive criticism. Your teacher cannot actually help you write your EE. The IB recommends that the supervisor spends approximately two to three hours in total with the candidate discussing the EE.

#5: Make Sure Your Essay Has a Clear Structure and Flow

The IB likes structure. Your EE needs a clear introduction (which should be one to two double-spaced pages), research question/focus (i.e., what you're investigating), a body, and a conclusion (about one double-spaced page). An essay with unclear organization will be graded poorly.

The body of your EE should make up the bulk of the essay. It should be about eight to 18 pages long (again, depending on your topic). Your body can be split into multiple parts. For example, if you were doing a comparison, you might have one third of your body as Novel A Analysis, another third as Novel B Analysis, and the final third as your comparison of Novels A and B.

If you're conducting an experiment or analyzing data, such as in this EE , your EE body should have a clear structure that aligns with the scientific method ; you should state the research question, discuss your method, present the data, analyze the data, explain any uncertainties, and draw a conclusion and/or evaluate the success of the experiment.

#6: Start Writing Sooner Rather Than Later!

You will not be able to crank out a 4,000-word essay in just a week and get an A on it. You'll be reading many, many articles (and, depending on your topic, possibly books and plays as well!). As such, it's imperative that you start your research as soon as possible.

Each school has a slightly different deadline for the Extended Essay. Some schools want them as soon as November of your senior year; others will take them as late as February. Your school will tell you what your deadline is. If they haven't mentioned it by February of your junior year, ask your IB coordinator about it.

Some high schools will provide you with a timeline of when you need to come up with a topic, when you need to meet with your advisor, and when certain drafts are due. Not all schools do this. Ask your IB coordinator if you are unsure whether you are on a specific timeline.

Below is my recommended EE timeline. While it's earlier than most schools, it'll save you a ton of heartache (trust me, I remember how hard this process was!):

• January/February of Junior Year: Come up with your final research topic (or at least your top three options).
• February of Junior Year: Approach a teacher about being your EE advisor. If they decline, keep asking others until you find one. See my notes above on how to pick an EE advisor.
• April/May of Junior Year: Submit an outline of your EE and a bibliography of potential research sources (I recommend at least seven to 10) to your EE advisor. Meet with your EE advisor to discuss your outline.
• Summer Between Junior and Senior Year: Complete your first full draft over the summer between your junior and senior year. I know, I know—no one wants to work during the summer, but trust me—this will save you so much stress come fall when you are busy with college applications and other internal assessments for your IB classes. You will want to have this first full draft done because you will want to complete a couple of draft cycles as you likely won't be able to get everything you want to say into 4,000 articulate words on the first attempt. Try to get this first draft into the best possible shape so you don't have to work on too many revisions during the school year on top of your homework, college applications, and extracurriculars.
• August/September of Senior Year: Turn in your first draft of your EE to your advisor and receive feedback. Work on incorporating their feedback into your essay. If they have a lot of suggestions for improvement, ask if they will read one more draft before the final draft.
• September/October of Senior Year: Submit the second draft of your EE to your advisor (if necessary) and look at their feedback. Work on creating the best possible final draft.
• November-February of Senior Year: Schedule your viva voce. Submit two copies of your final draft to your school to be sent off to the IB. You likely will not get your grade until after you graduate.

Remember that in the middle of these milestones, you'll need to schedule two other reflection sessions with your advisor . (Your teachers will actually take notes on these sessions on a form like this one , which then gets submitted to the IB.)

I recommend doing them when you get feedback on your drafts, but these meetings will ultimately be up to your supervisor. Just don't forget to do them!

The early bird DOES get the worm!

How Is the IB Extended Essay Graded?

Extended Essays are graded by examiners appointed by the IB on a scale of 0 to 34 . You'll be graded on five criteria, each with its own set of points. You can learn more about how EE scoring works by reading the IB guide to extended essays .

• Criterion A: Focus and Method (6 points maximum)
• Criterion B: Knowledge and Understanding (6 points maximum)
• Criterion C: Critical Thinking (12 points maximum)
• Criterion D: Presentation (4 points maximum)
• Criterion E: Engagement (6 points maximum)

How well you do on each of these criteria will determine the final letter grade you get for your EE. You must earn at least a D to be eligible to receive your IB Diploma.

Although each criterion has a point value, the IB explicitly states that graders are not converting point totals into grades; instead, they're using qualitative grade descriptors to determine the final grade of your Extended Essay . Grade descriptors are on pages 102-103 of this document .

Here's a rough estimate of how these different point values translate to letter grades based on previous scoring methods for the EE. This is just an estimate —you should read and understand the grade descriptors so you know exactly what the scorers are looking for.

Here is the breakdown of EE scores (from the May 2021 bulletin):

How Does the Extended Essay Grade Affect Your IB Diploma?

The Extended Essay grade is combined with your TOK (Theory of Knowledge) grade to determine how many points you get toward your IB Diploma.

To learn about Theory of Knowledge or how many points you need to receive an IB Diploma, read our complete guide to the IB program and our guide to the IB Diploma requirements .

This diagram shows how the two scores are combined to determine how many points you receive for your IB diploma (3 being the most, 0 being the least). In order to get your IB Diploma, you have to earn 24 points across both categories (the TOK and EE). The highest score anyone can earn is 45 points.

Let's say you get an A on your EE and a B on TOK. You will get 3 points toward your Diploma. As of 2014, a student who scores an E on either the extended essay or TOK essay will not be eligible to receive an IB Diploma .

Prior to the class of 2010, a Diploma candidate could receive a failing grade in either the Extended Essay or Theory of Knowledge and still be awarded a Diploma, but this is no longer true.

Figuring out how you're assessed can be a little tricky. Luckily, the IB breaks everything down here in this document . (The assessment information begins on page 219.)

40+ Sample Extended Essays for the IB Diploma Programme

In case you want a little more guidance on how to get an A on your EE, here are over 40 excellent (grade A) sample extended essays for your reading pleasure. Essays are grouped by IB subject.

• Business Management 1
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• Computer Science 1
• Economics 1
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• Environmental Systems and Societies 1
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• Geography 2
• Geography 3
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• Geography 5
• Geography 6
• Literature and Performance 1
• Mathematics 1
• Mathematics 2
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• Philosophy 1
• Philosophy 2
• Philosophy 3
• Philosophy 4
• Philosophy 5
• Psychology 1
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• Psychology 3
• Psychology 4
• Psychology 5
• Social and Cultural Anthropology 1
• Social and Cultural Anthropology 2
• Social and Cultural Anthropology 3
• Sports, Exercise and Health Science 1
• Sports, Exercise and Health Science 2
• Visual Arts 1
• Visual Arts 2
• Visual Arts 3
• Visual Arts 4
• Visual Arts 5
• World Religion 1
• World Religion 2
• World Religion 3

What's Next?

Trying to figure out what extracurriculars you should do? Learn more about participating in the Science Olympiad , starting a club , doing volunteer work , and joining Student Government .

Studying for the SAT? Check out our expert study guide to the SAT . Taking the SAT in a month or so? Learn how to cram effectively for this important test .

Not sure where you want to go to college? Read our guide to finding your target school . Also, determine your target SAT score or target ACT score .

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2016-2025 IB Extended Essay: Sample IB EE's

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• Chemistry 1
• What are the Alternative Fuels for the Depleting Fossil Fuels and which is the Best Fuel in Accordance with the Energy Output?
• A Copper Ions
• Chemistry 3

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• Does Hull Trim and Balance Affect the Speed of a Boat?

Individuals & Society:

• Market Form of the Retail Petroleum Supply Industry in Parklands
• Economics 1
• Economics 2
• Economics 3

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• Geography 2
• History EE (2018 new rubric)
• To What Extent was the Establishment of the State of Israel in Palestine in 1948, Influenced by Theodor Herzl?

Information Technology in a Global Society

• Philosophy 1
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• Philosophy 4
• Psychology EE (2018 new rubric)
• Applied Behavior Analysis and Early Intervention: The Extent of Recovery from Autism
• Psychology 1
• Psychology 2
• Psychology 3

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• Social & Cultural Anthropology 1
• Social & Cultural Anthropology 2

World Religions

• To What Extent do the Core Scriptural Teachings of Sikhism Permit them to Marry Outside of the Religion?
• World Religions 1
• World Religions 2

Language Acquisition:

• French: Les Liaisons Dangereuses

Literature & Language 

•   Journeys in the Inferno and The Wonderful Wizard of Oz   
•   Toni Morrison 

Math: 

•   Cryptography and Rubik's Cube: An Investigative Analysis   
•   Pascal's Triangle 

Visual Arts: 

•   How Does the work of Yinka Shonibare Illustrate the Changing Role of African Art in a Global Society? 
• Ballet's Accessibility and Costumes Affecting Society's View of the Art Form
• Visual Arts 1
• Visual Arts 4

Interdisciplinary Essays:

Environmental Systems & Societies

• ESS Extended Essay (2018 new rubric)

World Studies

• World Studies EE History, Economics, & Politics  (2018 new rubric)
• Does the Production of Dairy and Meat from Dairy Cows in the United States affect the Environment and Well Being of Animals and Humans?
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Why is biology important?

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What is biology?

Biology is a branch of science that deals with living organisms and their vital processes. Biology encompasses diverse fields, including botany , conservation , ecology , evolution , genetics , marine biology , medicine , microbiology , molecular biology , physiology , and zoology .

As a field of science , biology helps us understand the living world and the ways its many species (including humans ) function, evolve, and interact. Advances in medicine , agriculture , biotechnology , and many other areas of biology have brought improvements in the quality of life. Fields such as genetics and evolution give insight into the past and can help shape the future, and research in ecology and conservation inform how we can protect this planet’s precious biodiversity .

Where do biology graduates work?

Biology graduates can hold a wide range of jobs, some of which may require additional education. A person with a degree in biology could work in agriculture , health care, biotechnology , education, environmental conservation, research, forensic science , policy, science communication, and many other areas.

biology , study of living things and their vital processes. The field deals with all the physicochemical aspects of life . The modern tendency toward cross-disciplinary research and the unification of scientific knowledge and investigation from different fields has resulted in significant overlap of the field of biology with other scientific disciplines . Modern principles of other fields— chemistry , medicine , and physics , for example—are integrated with those of biology in areas such as biochemistry , biomedicine, and biophysics .

Biology is subdivided into separate branches for convenience of study, though all the subdivisions are interrelated by basic principles. Thus, while it is custom to separate the study of plants ( botany ) from that of animals ( zoology ), and the study of the structure of organisms ( morphology ) from that of function ( physiology ), all living things share in common certain biological phenomena—for example, various means of reproduction , cell division , and the transmission of genetic material.

Biology is often approached on the basis of levels that deal with fundamental units of life. At the level of molecular biology , for example, life is regarded as a manifestation of chemical and energy transformations that occur among the many chemical constituents that compose an organism. As a result of the development of increasingly powerful and precise laboratory instruments and techniques, it is possible to understand and define with high precision and accuracy not only the ultimate physiochemical organization (ultrastructure) of the molecules in living matter but also the way living matter reproduces at the molecular level. Especially crucial to those advances was the rise of genomics in the late 20th and early 21st centuries.

Cell biology is the study of cells—the fundamental units of structure and function in living organisms. Cells were first observed in the 17th century, when the compound microscope was invented. Before that time, the individual organism was studied as a whole in a field known as organismic biology; that area of research remains an important component of the biological sciences. Population biology deals with groups or populations of organisms that inhabit a given area or region. Included at that level are studies of the roles that specific kinds of plants and animals play in the complex and self-perpetuating interrelationships that exist between the living and the nonliving world, as well as studies of the built-in controls that maintain those relationships naturally. Those broadly based levels— molecules , cells, whole organisms, and populations—may be further subdivided for study, giving rise to specializations such as morphology , taxonomy , biophysics, biochemistry, genetics , epigenetics , and ecology . A field of biology may be especially concerned with the investigation of one kind of living thing—for example, the study of birds in ornithology , the study of fishes in ichthyology , or the study of microorganisms in microbiology .

Basic concepts of biology

Biological principles.

The concept of homeostasis —that living things maintain a constant internal environment—was first suggested in the 19th century by French physiologist Claude Bernard , who stated that “all the vital mechanisms, varied as they are, have only one object: that of preserving constant the conditions of life.”

As originally conceived by Bernard, homeostasis applied to the struggle of a single organism to survive. The concept was later extended to include any biological system from the cell to the entire biosphere , all the areas of Earth inhabited by living things.

All living organisms, regardless of their uniqueness, have certain biological, chemical, and physical characteristics in common. All, for example, are composed of basic units known as cells and of the same chemical substances, which, when analyzed, exhibit noteworthy similarities, even in such disparate organisms as bacteria and humans . Furthermore, since the action of any organism is determined by the manner in which its cells interact and since all cells interact in much the same way, the basic functioning of all organisms is also similar.

There is not only unity of basic living substance and functioning but also unity of origin of all living things. According to a theory proposed in 1855 by German pathologist Rudolf Virchow , “all living cells arise from pre-existing living cells.” That theory appears to be true for all living things at the present time under existing environmental conditions. If, however, life originated on Earth more than once in the past, the fact that all organisms have a sameness of basic structure, composition , and function would seem to indicate that only one original type succeeded.

A common origin of life would explain why in humans or bacteria—and in all forms of life in between—the same chemical substance, deoxyribonucleic acid ( DNA ), in the form of genes accounts for the ability of all living matter to replicate itself exactly and to transmit genetic information from parent to offspring. Furthermore, the mechanisms for that transmittal follow a pattern that is the same in all organisms.

Whenever a change in a gene (a mutation ) occurs, there is a change of some kind in the organism that contains the gene. It is this universal phenomenon that gives rise to the differences ( variations ) in populations of organisms from which nature selects for survival those that are best able to cope with changing conditions in the environment .

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Biology vs. Chemistry: A Major Decision

Jan 26, 2021

Trying to weigh the big decision: biology vs. chemistry? Read on to learn about what makes each discipline unique so you can make the most well-informed decision about becoming a biology, chemistry, or biochemistry major .

What will I learn in biology courses? 

Biology is the study of life, meaning anything that eats and breathes falls under the subject. What you do with living things covers a range of skills including classifying them, charting their evolution, cataloging their various forms, and of course studying how they’re put together.

As you most likely know, biology is a natural science—along with physics, chemistry, astronomy, and Earth science—from which other, more specialized areas of science begin. As such, the study of biology lends itself to a wide range of skills and concepts that can be applied to a host of different careers. 

Biology teaches data analysis first and foremost. In your courses, you’ll learn how to gather information quantitatively and then determine what the numbers tell you. “Just because” is never enough for biologists, as every hunch must be backed up by numerical data. Once you get a handle on what data tells you, you’ll learn to predict trends and behavior based on factors at hand. Biology involves acting to prevent problems in living things as much as reacting to and studying what they do.

Biology is not all numbers, however. Scientific data is often difficult or intimidating for audiences, so biologists have to be experts in clear, concise presentation of ideas through both their speaking and writing.

A biology student should be in love with the scientific method—knowing how to design and execute experiments. Identifying constants and variables and running plenty of tests to make sure you are ready for any eventuality are skills that cross many disciplines, but biology absolutely depends on these skills.

You also need to be comfortable, and preferably excited, about learning the latest technology and trying new tools. Any scientist needs to be at one with their instruments, so gadget love is a big plus.

What can I do with my bachelor's degree in biology?

More like what can't  you do. Biology is a gateway to a lot of career paths, and a grounding in the subject will always be highly sought after by employers.

You’ll soon find you can stop asking, “ What can you do with a biology degree ?” and discover that biology has numerous specific concentrations, and choosing one will do a lot to help you focus your career options. You can become a marine biologist, studying aquatic life; a microbiologist, specializing in living things you can’t see with the naked eye; you can work in genetics, looking at heredity and how beings evolve; bioinformatics, using computer technology to predict and detail natural occurrences; or biochemistry, which we will discuss more later.

You probably think first of biology leading to a job doing research, and that’s true—a lot of biologists make time in the lab during their career. They work primarily for academic institutions on specific projects, publishing studies and reviewing articles from others. Lab jobs can also be part of private companies or government offices, working on product testing or prevention of infectious diseases.

Biology degrees can also lead to work in environmental management, helping consulting firms and nonprofit organizations work on conservation efforts and generate information to help lobby the government. 

One of the more popular paths for a biology major is going into healthcare, whether as a medical doctor, medical researcher, nurse practitioner, public health specialist, dentist or veterinarian. On the other hand, biology may lead you on a path to a different degree, such as one in public health. If this interests you, see more to answer the question “ What is a public health degree ?” on our blog!

Another popular area stemming from biology is engineering, specifically applying engineering principles to living systems. Biological engineers can work in healthcare designing medical devices, in environmental science agencies creating cleaner and more efficient ways to process fuel, or with major manufacturers and farms helping to create sustainable ways to produce food and protein. 

Other jobs biology majors tend to get that may be a bit surprising are personal trainers, dieticians and nutritionists, and writers and illustrators for scientific textbooks, guides and journals.

And you can always do more within the educational world, by going for an advanced degree in biology, or doing advanced research and teaching as a biology faculty member at a college or university.

Is it a good idea to get into biology careers?

We mentioned above that there is always demand for expertise in biology, but it is important to know just how much. The U.S. Bureau of Labor Statistics (BLS) predicts that over the next six years or so, common jobs of biology majors are going to be in higher demand, not lower. Healthcare, business and engineering jobs coming from biology backgrounds will grow the most, unfortunately because of the mounting challenges to our bodies and the environment.

Going into dentistry is one lucrative example—the BLS predicts 19% growth for dental professionals through 2026 with an average annual salary of over $156,000. Some more specific examples of jobs that will see growth through 2026 include zoologists (8% growth), biochemists (11%), medical scientists (13%) and genetic counselors (29%).

As with most industries, the jobs bio majors tend to get correspond to your highest degree and experience level. While you might have to work your way up with an associate’s or bachelor’s degree, you can walk into a high-paying position as a researcher or consultant if you have a master’s or doctoral degree in biology. But in any case, a biology degree is a good place to start. According to Payscale, the average starting salary for biology majors in entry-level jobs is $53K, rising to $102K for biology majors late in their careers.

What will I learn in chemistry courses?

Beyond many of the same basic skills you get from biology, chemistry—the study of how substances are put together as well as how they transform over time—goes into great detail on scientific ethics. Chemical testing involves a lot of complicated processes that can be potentially hazardous. Not to mention that effective results of chemical experimentation, specifically in organic chemistry, can sometimes only come from testing on living things. Being able to balance the value of safety with the need for scientific development can be fraught, and so a chemist has plenty of opportunities to wrestle with ethical questions.

Chemistry students also need to be creative. So much of the science relies on testing chemical reactions, so a chemist needs to be willing to try combinations and work from a careful combination of theories and facts to find out more about natural life. Inorganic chemistry and synthetic chemistry depend on new ways of looking at the chemical composition of objects and uncovering their unknown properties.

You will also learn to see things as the sum of their parts. Analytical chemistry includes a lot of separating substances into their components to find out how they come together. You’ll become precise in your exploration and able to see complicated patterns of structure where others only see a flat picture.

What can I do with a bachelor’s degree in chemistry?

Similar to a biology major, careers in chemistry are often dependent on what area of chemistry you specialize in. Pre-health is a common path for chemistry majors, leading to careers in drug and medicine development—finding cures, therapies and even preventive measures for a wide range of diseases and physical problems.

Another popular route for chemistry majors is to get into forensic chemistry, where you can apply your skills to aid in criminal investigations. Not only will you need to be well-versed in toxicology, osteology—the study of the structure and function of the human skeleton and bones—and textile chemistry, but you’ll need to know a lot about the criminal justice system.

Chemical engineering is the area a lot of people associate most closely with chemistry. This is where you use your chemical knowledge to help produce consumer products, like food and fuel, as well as medical devices like drug delivery systems and even artificial organs. You can also work closely with architects, designing the structural elements of buildings as well as inspecting them to make sure they are safe, up to code, and structurally sound.

As with biology, there are also plenty of government and educational jobs waiting for those with a degree in chemistry. You could be a development researcher for the military or NASA, a consultant for the auto industry, or a policy specialist helping get laws written regarding drugs and other industrial materials. And of course you can research or teach at a college or university, or teach at the junior high and high school levels if you like the idea of working with younger children.

Then there is biochemistry, sometimes called biological chemistry, where these two main areas meet. This is where scientists seek an understanding of chemical reactions in biological systems. If you are interested in what happens when we or other animals eat, how four chemicals can add up to the human gene sequence of every living thing, how and why we get sick, or how blood carries so much importance in keeping the body going, then you should explore this cross-section of chemistry and biology.

Jobs in biochemistry tend to involve a lot of lab time as a researcher, but they can cross areas from medicine to drug design and pharmaceuticals to corporate work. If interested in pharmaceuticals, make sure you are aware of all the pharmacist education requirements .

How is the money and job security for chemistry careers?

Like biology careers, jobs for chemists are also on the rise, with a predicted 4% growth through 2028 , according to the BLS. That should add up to about 3,500 jobs added to the U.S. economy over 10 years. Some of the fastest-growing positions are registered nurses (12% occupational growth) and food scientists (7%).

The value of a career in chemistry is just as dependent on time in school and experience as one in biology, but unlike biologists where medicine is the most secure path, the most secure jobs for chemists are in supplying to pharmaceutical companies. Drug manufacturers are the biggest employers of chemists in the United States , according to Data USA, with more than 300,000 employees in this country making an average annual salary of more than $104K. 

Government jobs are harder to come by, as you might imagine, and pay closer to an average salary over $114K. There are also successful careers to be had in architecture and engineering ($67K), research ($92K), and manufacturing of non-health-related chemicals ($88K).

Which one do I choose, Biology or Chemistry?

Ultimately, the choice comes down to what you want to spend most of your time doing over the next few years. Both chemistry and biology will give you plenty of opportunities to learn complicated systems, perform experiments, analyze data and dig under the surface of what we observe in the world every day.

Biology includes a set of a hard and fast rules, and involves a bit more observation and noting of facts. Chemistry, meanwhile, is a bit more about trial and error, breaking things down to build them back up again. A biology major will be more likely to put you in the classroom or in the field while chemistry will have you in the lab.

There’s also the question of motivation. Certainly not always, but generally speaking, biology tends to be about the study and protection of living things. It can be plenty lucrative, but is often not geared in that direction. Chemistry, by contrast, can be more about entrepreneurship and developing products that will improve people’s lives, including yours when those products are sold. Chemists still do plenty of good for the world, too, but as a set of careers, chemistry represents goods and biology represents services.

Whichever you choose, you will want to study the subject at a reputable school with proven faculty and excellent facilities. North Central College offers degree programs in biology , chemistry and biochemistry , with top-flight internships and partnerships with some of the leading companies in America, cutting-edge technology to keep you up-to-date with the skills and expertise employers want, and opportunities to do research from your first day of college.

Find out more and learn how to apply at northcentralcollege.edu/apply .

Jacob Imm is a communications specialist in the North Central College Office of Marketing and Communications. He has 10 years of collegiate communications experience and has worked with hundreds of college students. He has a bachelor’s degree from the University of Notre Dame and a master’s degree from Northern Illinois University.

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chemistry vs biology

Updated 13 July 2022

Subject Experience ,  Learning ,  School

Downloads 49

Category Education ,  Life

Topic Importance of Education ,  Middle School ,  Personal Experience

I discovered in middle school that Chemistry involves the mixing of solvents and solutes to form a solution.

On the same note, I discovered that biology is the science of living things such as plants, animals, and bacteria. All in Middle School understands the distinctions between Chemistry and Biology. These are the main concepts of Chemistry and Biology, according to a layperson's interpretation. Despite their discrepancies, the two topics are related. As a result, Chemistry serves as the primary biological factor, implying that Biology does not survive without Chemistry. As a result, Chemistry and Biology are associated topics. The University of Arizona considers Chemistry as a related subject to Biology. As such, Chemistry has four elements, which make the 99 percent of all the living things. These elements are Oxygen (O), Carbon (C), Hydrogen (H), and Nitrogen (N) (The University of Arizona 1). Hence, there would be no life without the presence of these elements in the biosphere.

It is the Chemistry, which ensures that organs of all living things are attached and linked to each other.

Hence, there are attractions, which results in the development of longer constructions, which include the foot and the hand. Furthermore, the food that living things consume comprises of Chemistry. The Chemistry helps in breaking down such foods into smaller molecules for ready absorption in the body of people.

Biology and Chemistry focuses on the study of life, but in different perspectives.

Biology is considered as the study of living things and their interactions with the immediate environment (Region of Queens Municipality 1). Hence, biology focuses on the study of all living things as they exist within their natural environment. This is different from Chemistry since Biology aims at organs and organisms and how such organs function while Chemistry focuses on the minuscule components of the make-up of these structures in the body of living things.

Both Biology and Chemistry are sciences, which assist in seeing the differences, which exists in the modern life.

For example, Chemistry assists in making clarifications as to why a dog looks different from a cat by taking into consideration of the genetic composition of these animals. Chemist professionals embark on natural diversity to develop polymers, designs, and pharmaceutical synthesis that help in the environmental protection and the development of other alternatives of energy sources in society (Region of Queens Municipality 1). On the other hand, Biology assists in understanding the structural difference between a dog and a cat in relation to lineage. Thus, biologists utilize a hierarchy of biological organization to illustrate the connectivity and the position of all the living things. The hierarchy begins from the molecules to the cells of the organisms, which are present in the ecosystem of both animals and plants (Region of Queens Municipality 1).

Thus, when in a Biology class doing the frog dissection, it is good to recall that it is Chemistry, which ensures the existence of the frog.

As such, Chemistry is the key life component, which dictates the existence of people in society. It acts as the key factor for people to eat food and for such food to nourish human bodies. The genetic make-up of a living organism determines how Chemistry helps in the production of different structures.

Works Cited

Region of Queens Municipality. Biology and Chemistry. Web. 2nd Feb, 2017.

The University of Arizona. Department of biochemistry and molecular biophysics.

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UNIV 325: Science Fellowship Application Workshop: Biology/Chemistry

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• MicroBiology Open MicrobiologyOpen is an open access journal that is your prime source for understanding microbial science and biotech, bringing these evolving fields together in this exciting, post-genomic era.
• GenBank GenBank ® is the NIH genetic sequence database, an annotated collection of all publicly available DNA sequences
• Science.gov cience.gov is a U.S. government website providing a search tool for finding scientific and technical information from across top U.S. federal agencies.
• Data.gov The Home of the U.S. Government's Open Data: here you will find data, tools, and resources to conduct research, develop web and mobile applications, design data visualizations, and more.
• PubChem PubChem is the world's largest collection of freely accessible chemical information. Search chemicals by name, molecular formula, structure, and other identifiers. Find chemical and physical properties, biological activities, safety and toxicity information, patents, literature citations and more.
• ChemSpider The Royal Society of Chemistry publishes over 50 world-leading journals that span the core chemical sciences and related fields. Known for rigorous, fair peer review and fast publication times, our journals publish the best science, from original research articles to authoritative reviews.
• U.S. Department of Energy Office of Scientific and Technical Information The Department of Energy (DOE) Office of Scientific and Technical Information (OSTI), a unit of the Office of Science, fulfills agency-wide responsibilities to collect, preserve, and disseminate both unclassified and classified scientific and technical information (STI) emanating from DOE-funded research and development (R&D) activities at DOE national laboratories and facilities and at universities and other institutions nationwide.
• SCOPe Structural Classification of Proteins — extended) is a database developed at the Berkeley Lab and UC Berkeley. SCOPe classifies many structures released since SCOP 1.75 through a combination of automation and manual curation, and corrects some errors, aiming to have the same accuracy as the fully hand-curated SCOP releases. SCOPe also incorporates and updates the Astral database.
• Molecular Biology and Evolution
• Microbiology and molecular biology reviews
• Molecular and cellular biology
• Organic & biomolecular chemistry
• Physical chemistry chemical physics
• Chemical communications  
• Developmental biology
• Experimental biology and medicine
• Journal of evolutionary biology

This link will take you to a catalog results page for all chemistry, biology, and molecular biology journal results. 

Note that if a call number / location of an item says "Offsite Storage" this means it is in a secured location. If you want to view an item from Offsite Storage, visit TheDesk in Roy O. West and provide the item you are looking for. Since they will need to go to Julian to retrieve the item it can take a few minutes. Note, that it will help them find your item as efficiently as possible if you provide the exact journal name, issue, and volume number. 

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• Last Updated: Sep 27, 2024 8:06 AM
• URL: https://libguides.depauw.edu/c.php?g=1427174