Each of the 20 amino acids has a specific side chain, known as an R group, that is also attached to the α carbon. The R groups have a variety of shapes, sizes, charges, and reactivities.

This image illustrates the general structure of an amino acid.The central carbon atom (C) is bonded to a hydrogen atom (H), an amino group (NH2), a carboxyl group (COOH), and a variable side chain (R ...

In fact, each gene in cellular DNA contains the code for a unique protein structure ... acids, which are small organic molecules that consist of an alpha (central) carbon atom linked to an amino ...