Biochemists study biochemistry, which is the chemistry of life. Studying biochemistry can offer insights into how organisms function at their most basic level, which can eventually lead to advances in medicine. The biochemistry underlying life for most organisms is surprisingly similar, from single-celled bacteria, yeast, and algae to plants, fruit flies, and humans.
Organisms use only a few of the elements on the periodic table to create a remarkable diversity of molecules. Carbon, hydrogen, oxygen, and nitrogen together account for over 96% of the mass of the human body, and these elements can be combined in countless permutations, allowing the formation of the building blocks of life. The major building blocks of biochemistry include amino acids, nucleic acids, carbohydrates, and lipids. These building blocks in turn combine in myriad iterations to form the macromolecules of biochemistry: amino acids combine to form proteins, carbohydrates combine to form starch, glycogen, and cellulose, nucleic acids polymerize into DNA and RNA, and lipids group together to form membranes that define the most basic unit of life, a cell.
Biochemists study the way that proteins, DNA and RNA, sugars, and lipid membranes are made, their structures, and their functions. This, in turn, can lead to understanding what sometimes goes wrong in cells or diseases, and ultimately how that can be repaired.
Biological molecules are made inside of a cell, by other biological molecules. Deoxyribonucleic acid (DNA) is the blueprint for a cell, and can be copied into ribonucleic acid (RNA). The RNA copied from DNA is then translated into proteins, which carry out the brunt of reactions inside a cell. Different proteins catalyze a huge variety of chemical reactions, allow the transport of small molecules and ions into and out of cells, assist the proper folding of other proteins and the degradation of improperly folded proteins, and provide a scaffold onto which DNA is compacted, to name a few examples.
Of course, no biological molecule acts alone: understanding how biological molecules interact with each other is a crucial part of biochemistry. Some proteins bind DNA to regulate whether, when, where, and how much the DNA is transcribed into RNA. Proteins can perform reactions on other proteins, for example regulate another protein's activity level by adding a phosphate group onto that protein. Many proteins also carry out reactions on sugar molecules, and these types of reactions comprise the core of metabolism.
Typically, biochemists try to replicate cellular reactions in a test tube to understand how these molecules work inside a cell. By first grasping how the molecules work in a minimal environment, biochemists can then predict what will happen as more and more complex substrates or effectors are added into the test tube.
In general, as details of biochemistry are unveiled, biochemists realize that more and more questions are brought up by the answers they have discovered. Until the beautiful complexity of life is fully understood, biochemists have plenty of work ahead of them.