The four main categories of biomolecules are carbohydrates, lipids, proteins and nucleic acids. While there are some special cases to be found, these four molecules make up the bulk of living bodies, and each plays an essential role in regulating the body's chemistry.
Carbohydrates are the starches and sugars that bodies use for energy. Brains, for example, consume large amounts of glucose with consumption rising in areas of the brain that are the most active. Lipids help the body store the energy it needs in the form of fats and oils. Wax, of the type secreted by honeybees, is another form of lipid. Proteins are the workhorses of the body's machinery. Proteins carry out specific functions inside cells, and they act as enzymes to catalyze reactions all over the body. Amylase, lactase and pepsin are all proteins used in digestion, for example. Proteins are typically large molecules that can be built up from chains of amino acids called polypeptides. Nucleic acids are central to the function of living cells. Arranged in a linear sequence within DNA, they code for the structure and function of the body's proteins. Nucleic acids also form RNA, which acts to transmit DNA-based instructions to the cellular machinery.