A macromolecule derived from natural sources; also known as biological polymer. Nature has developed effective means for efficiently preparing and utilizing biopolymers. Some are used as structural materials, food sources, or catalysts. Others have evolved as entities for information storage and transfer. Familiar examples of biopolymers include polypeptides, polysaccharides, and polymers derived from ribonucleic acid (RNA) and deoxyribonucleic acid (DNA). Other examples include polyhydroxybutyrates, a class of polyesters produced by certain bacteria, and cis-1,4-polyisoprene, the major component of rubber tree latex.