Flexi Says: When amino acids bind together, they form a long chain called a polypeptide. A protein consists of one or more polypeptide chains. A protein may have up to four levels of structure. The lowest level, a protein’s primary structure, is its sequence of amino acids. Higher levels of protein structure are described in Figure below. The complex structures of different proteins give them unique properties, which they need to carry out their various jobs in living organisms.
