amino acid group, a category of organic chemicals containing an amino group (NH2), a carboxylic acid group (COOH), and a variable R group on the carbon separating the amino and carboxyl groups (often referred to as the alpha carbon). The R group may be comprised of nonpolar, polar, acidic, or basic side chains. The presence of the R group creates defined three-dimensionality which is conserved in all naturally occurring amino acids.
