Polypeptide

A polypeptide is a string or linear chain of amino acids linked together. Amino acids are the basic building blocks of proteins. A single polypeptide chain might make up the entire primary structure of a simple protein; more complex proteins are formed when two or more polypeptides link together. Each protein is a polymer of amino acids.
Polypeptides are made when mRNA is translated, a process involving ribosomes, tRNA and amino acids.