Amino acids are organic compounds that combine to form proteins and are used by the body for growth, repair, and the production of enzymes, hormones, neurotransmitters, and other molecules.
The 20 amino acids humans require are grouped as:
essential amino acids which must come from the diet as the body does not manufacture sufficient quantities even under normal conditions
At the chemical level, amino acids generally contain an amino group (-NH₂) and a carboxyl group (-COOH), with a variable side chain (R group) that determines their properties.