Amino acids are essential building blocks of proteins, and they can be found in every living organism. They play an important role in various biological processes such as metabolism, cell growth, and tissue repair. They are organic compounds where each molecule has a central carbon atom linked together with an amino group, a carboxylic acid group, a hydrogen atom, and an R group (or side chain) that is unique to each amino acid. They are precursors to other molecules including proteins, hormones, and neurotransmitters.