Amino acid

Amino acids are the main components of proteins. Twenty types are classified scientifically as “important” and, of those, half are considered “essential” for human survival. A living cell creates protein when two amino acids link to form a bond. This first group is then linked to a third, and so on, until a long chain is produced. This chainlike molecule may contain up to several hundred amino acid subgroups or links. A protein may be formed of a single chain, or it may consist of several chains held together by molecular bonds. Most plants are able to make all the amino acids they require for growth. Humans, however, must obtain some of the standard amino acids from their diet; these amino acids are called “essential” and include lysine, tryptophan, valine, histidine, leucine, isoleucine, phenylalanine, threonine, methionine, and arginine. They are found in protein-rich foods from animal sources (such as meat and dairy products) and in some plant proteins. The process of breaking down these bonded proteins is a large part of both cooking and digesting food.