Amino acids are a set of 20 different molecules used to build proteins. Proteins consist of one or more chains of amino acids called polypeptides. The sequence of the amino acid chain causes the polypeptide to fold into a shape that is biologically active. The amino acid sequences of proteins are encoded in the genes.
Amino acids are the small molecules that are put together to make proteins. And so there are 20 different amino acids. You can think of it as different flavors that get linked together like beads on a string to make long chains that we call polypeptides, and those are the building blocks of proteins. And the really neat thing about the amino acids is that when they're linked together, they fold to make the final shape of the protein. And it's the shape of the protein that really dictates what it can do in the cell.- Lawrence C. Brody, Ph.D.