Wool is a polymer made of protein. Wool fiber is primarily composed of a protein called keratin. Proteins are natural polymers made up of repeating units of amino acids linked by peptide bonds. Rubber (natural rubber) is a polymer of isoprene, a hydrocarbon. Cotton and Jute are natural fibers composed primarily of cellulose, which is a polysaccharide (a polymer of glucose units). These are carbohydrate polymers, not protein polymers.