Biopolymers are polymers produced by living organisms. Biopolymers contain monomeric units that are covalently bonded to form larger structures. These are three main classes of biopolymers, that is monomers, polypeptides and polynucleotides. Other examples of biopolymers include suberin, melanin and lignin. Dextron is a copolymer of glycolic acid and lactic acid.