Amino acids

Definition

Amino-acids are the building blocks of protein. Chemically, an amino-acid is a molecule containing a basic amino group (-NH2), an acidic carboxyl group (-COOH) and an organic R group (or side chain) which is unique to each amino acid. A condensation reaction links two amino acids together with the loss of -OH from the carboxyl group of one AA together with a hydrogen from the amino group of the second, losing a molecule of water and leaving the two AAs linked via an amide – called a peptide bond. There are 20-22 amino-acids that comprise proteins. All have the same basic structure, differing only in the R group or side chain.