The polysaccharides are the polymers of monosaccharide. They are complex starches and cellulose. Simple sugars or monosaccharide subunit join to form the polysaccharides.
Functions of polysaccharides:
1. Starch and glycogen are the major storage polysaccharides
2. Starch and glycogen also serve as a source of energy. They are hydrolyzed to their constituent glucose monomer units by specific enzyme actions.
3. Cellulose and chitin are the main structural polysaccharides.
4. Cellulose occurs in the cell wall of most algae, all higher plants and certain fungi and protists. Cellulose has a roughage value for human beings. Cellulose forms the food for ruminant, snails and termites.
5. Chitin occurs in the cell wall of many fungi and in the exoskeleton of arthropods.
6. Peptidoglycan occurs in the cell wall of bacteria.
7. Hyaluronic acid acts as a lubricant at the joints and as a cement substance to fix the follicle cells to the eggs.
8. Heparin act as an anticoagulant and prevents the clotting of blood in the blood vessels of animals
9. Glycoproteins form a protective covering, called, glycocalyx on the intestinal lining.
10. Mucilage forms protective covering around bacteria, algae and aquatic plants. It is derived from polysaccharides.
11. Some mucopolysaccharides have certain medicinal value, such as husk of Plantago ovate, Mucilage of aloe, and alginic acid, agar, carrageen etc. of marine animals.
12. Some pectin is used as commercial jellying agents.
13. The cellulose of plant cell walls and the chitin of insect exoskeletons and fungal cell walls are used for providing mechanical support.
14. Glycoproteins and glycolipids are integral components found in cell membranes.
15. The surfaces of most cells are coated with sugar polymers belonging to glycoproteins and glycolipids in the cell membrane. These sugar side chains help in cell recognition.