Biochemistry is the study of the chemistry of living things. Put another way, biochemistry is the application of chemical concepts and understanding to biological processes. You can probably guess how the name biochemistry was chosen (hint: biology + chemistry = biochemistry). Typically, these biological processes occur at the cellular or molecular level, and biochemists study how those molecules form cells, tissues, and entire organisms.
Biochemistry as an area of study is relatively new; it started to be recognized as a separate discipline in the early 20th century as scientists utilized knowledge of chemistry, biology, and physiology to study the chemistry of living things. In contrast, modern chemistry emerged in the early 17th century, though its principles have been studied since ancient, early human times.
Biochemistry is considered “interdisciplinary” because it draws on knowledge and expertise from many other areas of study. Biochemistry serves as the base of many other areas of study like medicine, veterinary science, neuroscience, agriculture, and biotechnology. Knowledge of biochemistry is what helps scientists and researchers learn about new diseases and develop treatments or cures.
Plants, animals, and other organisms use the same or similar biochemical cycles and processes to live. For example, you have likely heard of photosynthesis, the process by which plants use water and carbon dioxide to produce oxygen and sugars. This is a biochemical process and is a form of carbon fixation because the carbon within the carbon dioxide is “fixed” into the sugar molecules. This process is clearly very important since all other organisms on Earth that do not perform photosynthesis rely on the products of photosynthesis (i.e. oxygen and sugar) to live! Photosynthesis is part of a larger cycle on Earth called the carbon cycle, which tracks the movement of carbon through the atmosphere, soil, water, and organisms on Earth.
Biochemical cycles make use of enzymes and proteins to move atoms and molecules around to the next appropriate location within the organism. The cycles transform some reactant molecules into desired product molecules, which serve a particular function in the organism. For example, the process of metabolism breaks down food-related molecules (e.g. sugar, protein, starch) into usable energy for the organism.
Some other well-known cycles are the Krebs cycle and the Calvin cycle. The Krebs cycle is also known as the citric acid cycle and is the energy-producing cycle that occurs in the mitochondria. You may have heard before that the mitochondria are the “powerhouses” of cells, and this cycle is at the heart of that reasoning. The Calvin cycle is somewhat similar and occurs in the chloroplasts of plants; this is the cycle in which carbon compounds are transformed.
Types of molecules that you may have heard of that are extremely relevant in biochemistry are carbohydrates, lipids, proteins, enzymes, nucleic acids, and amino acids. These are largely organic compounds, which means they contain carbon. We will only go into some basics about these molecules here.
When you hear the word carbohydrate, you likely think of breads and pastas. Actually, carbohydrates are just sugars, which contain lots of carbon atoms and are used to provide energy to organisms. Mono-, di-, and poly-saccharides are specific forms of sugar, so they also fall within the carbohydrate category.
Lipids are fats, steroids, and waxes (yes – including ear wax!) Fats, which can be saturated or unsaturated, are also called triglycerides. Fats are made of a molecule called glycerol, which contains a carbon chain that has connected fatty acids (which are also made of long chains of carbon atoms). Steroids are not just external drugs that people take; they exist naturally in animals within hormones. That said, you should never take steroid drugs unless prescribed by a doctor and never to enhance your body as an athlete.
The word protein probably makes you think of meat: chicken, beef, pork, fish. This is because those food items contain protein molecules. Proteins are very large molecules with complex structures, and they are important for a wide variety of processes within an organism or body. At the most basic level, though, proteins are made up of a string of amino acids, which we briefly describe below.
Enzymes are actually a type of protein. What makes them different than a general protein is that they are specialized and act as catalyst to perform specific functions in complex reactions. Because enzymes are very specialized, they are usually only able to perform one specific “task” (i.e. converting a specific reactant molecule into a specific product molecule), and then another enzyme has to perform the next task.
Examples of nucleic acids are DNA, RNA, mRNA, and tRNA (the NA in those terms stands for “nucleic acid”). All nucleic acids are made up of nucleotides, of which there are five. Those nucleotides are made up of a five-carbon sugar, a nitrogen-containing base, and a phosphate ion (PO43-).
There are over fifty different amino acids in existence. You may remember that we said proteins are made up of amino acids, but only twenty specific amino acids are used for that purpose. All amino acids contain a carboxyl group (COO–) and an amino group (NH2).
Now you have a little understanding of just how widespread biochemistry is in our world and how important biochemical processes are!