Amino acids, the building blocks of all protein molecules, are nitrogen-containing organic compounds that consist of at least one acidic carboxyl group (COOH) and one amino group (NH₂). These two groups are attached to a carbon atom, which also carries a hydrogen atom, plus a side chain known as the "R group." The R group varies from one amino acid to another and gives each amino acid its distinctive properties. Although relatively simple compounds, amino acids can vary widely and to date more than 80 different amino acids have been found in living organisms. Of these 80, 22 are considered the precursors of animal proteins.

The first few amino acids were discovered in the early 1800s. In 1806, the French chemist, Louis-Nicolas Vauquelin, isolated a compound in asparagus that proved to be the amino acid, asparagine. In 1812, William Hyde Wollaston found a substance in urine that he identified as a...