Nutrition Chemistry Review Proteins Proteins are the third major group of macromolecules that make up the bodies of organisms.
Proteins play diverse roles in living things.
Perhaps the most important proteins are enzymes, proteins capable of speeding up specific chemical reactions. Other short proteins called peptides are used as chemical messengers within your brain and throughout your body. Collagen, a structural protein, is an important part of bones, cartilage, and tendons. The identity and unique chemical properties of each amino acid are determined by the nature of the R group. Only 20 different amino acids make up the diverse array of proteins found in living things.