an 18-carbon saturated fatty acid. The normal numbering system, starting with the carboxylic acid, is shown in blue. The carbons and oxygens of the carboxylic acid functional group are red.

Chemically, an amino acid is a molecule that has a carboxylic acid group and an amine group that are each attached to a carbon atom called the α carbon. Each of the 20 amino acids has a specific ...