Sugars are the major energy storage molecules for living organisms.
Their carbon rings contain large amounts of energy. To distinguish between alpha and beta linkages, examine the position of the hydrogen on the first carbon molecule. In an alpha linkage, the hydrogen is pointing up, and in a beta linkage it is pointing down. Sucrose and lactose are composed of two sugars and are therefore termed disaccharides. Amylose and cellulose, composed of long chains of glucose molecules, are examples of polysaccharides.