Polypeptide

A polypeptide is a string or linear chain of amino acids linked together. Amino acids are the basic building blocks of proteins.^[1] A single polypeptide chain might make up the entire primary structure of a simple protein;^[2] more complex proteins are formed when two or more polypeptides link together. Each protein is a polymer of amino acids.^[3][4]

Tetrapeptide structural formulae N-terminus (Green) (N-terminus) and C-terminus (Blue) (C-terminus)

Polypeptides are made when mRNA is translated, a process involving ribosomes, tRNA and amino acids.