There are 4 levels of protein structure. The primary structure of a protein is the first level of protein structure and consists of amino acids in a row called a polypeptide chain. Different combinations of amino acids form different polypeptide chains. The shape and function of the protein is determined by the order of the amino acids in the polypeptide chain. The bond between each amino acid is called a peptide bond.
Source: concepts in Biology. 12th edition. Copywright 2007 McGraw-Hill
