A polypeptide is a single linear chain of many amino acids, held together by amide bonds. A protein can be made up of one or more polypeptide molecules.
The unique sequence of amino acids in a protein or polypeptide chain.
The local folding pattern within segments of a protein's polypeptide chain which includes alpha helices and beta sheets.
The overall three-dimensional shape resulting from folding and covalent cross-linking of a protein or polypeptide molecule.