Computer graphics representation of part of the long-chain molecule of starch, a polysaccharide. Saccharides or sugars are comprised of rings of 4 or 5 carbon atoms (green) and one oxygen atom (red). Attached around the ring are hydroxy (OH) groups. Glucose & fructose (monosaccharides) are comprised of single rings. Polysaccharides such as starch consist of various proportions of glucose polymers, amylose and amylopectin joined in a chain. Starch occurs widely in plants as a store of carbohydrate and is therefore a major source of energy for animals. Digestion of starch ultimately yields glucose. The image was modelled using Chemical Design's Chem-X software.