Amino acids are organic compounds containing a basic amino group and an acidic carboxyl group. Because amino acids contain both amino and carboxyl groups, they can be polymerized in an end-to-end manner, removing a molecule of water to form a covalent amide bond or peptide bond. Many amino acids are linked together end to end to form a polypeptide. Amino acids and peptides are important components in the fields of medicine and life sciences.