What is Biochemistry?


Study of the Chemistry of Living Things

DNA, enzymes, fats, carbohydrates, and hormones are all part of the discipline of Biochemistry.

On the interface between the disciplines of Biology and Chemistry, there is an area known as Biochemistry. This involves the study of what is going on in living cells on the molecular level.

Molecules in Cells

In a living cell, there are a variety of different types of molecules. Many are very large but are often made of repeating units, which in chemical terminology are called polymers. Using the tools of the chemist, a biochemist can study the content of these bio-molecules and also the reactions in which they are involved.


The study of biochemistry demonstrates the complexity of the contents and reaction pathways in even the tiniest, most simple cell. There are reaction cycles involving complicated enzymes and other compounds that depend on many different factors to correctly function. It is here that we begin to see the amazing complexity of life.


Much of what is called “life” depends on chemicals called proteins. These are polymers made up of repeating units called amino acids. Amino acids have a central carbon atom surrounded by four groups. One is a hydrogen atom. Two groups make the molecule an amino acid, first, there is an amino group (-NH2) and second a carboxylic acid group (-COOH). The final group is unique to each different amino acid. There are twenty standard amino acids that are used in living systems. Amino acids join together when the amino group reacts with the carboxylic acid group to make a peptide bond (-NH-CO-).

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Many proteins are used structurally in living things, but many others are used as enzymes. Enzymes are very long chains that fold up in specific ways because of the charges and other properties of the side groups. This macro-structure means that the enzymes act as very specific catalysts, creating specially shaped sites that take only the reagents needed and no others. In this way, important reactions happen immediately when needed.

Nucleic Acids

Another important type of biochemical is Nucleic Acids. There are two types of nucleic acid, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). These are complicated polymers made up of units called nucleotides. The main purpose of DNA is to store genetic information and to act as a pattern for the formation of important proteins.

Carbohydrates and Lipids

Carbohydrates and Lipids are the other major types of biochemical. Carbohydrates serve two main purposes, to provide cell structure and energy to the cell. There are some very important reaction cycles through which carbohydrates provide energy to drive other important reactions. Very large polymer carbohydrates are used to provide cell structure in plants, known as cellulose. Lipids are the fatty chemicals that provide energy to the cell, but many are dangerous to human health. Cholesterol and trans-fatty acids are types of lipids.

Biochemistry is a broad but fascinating subject in which principles developed in other chemistry disciplines are used to study the important molecular processes in living things.

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