BIO 1000 Lecture Notes - Lecture 5: Amylopectin, Polysaccharide, Starch

• School: St. John's University
• Department: Biology
• Course: BIO 1000
• Professor: Jai Dwivedi

Document Summary

Polysaccharides, the polymers of sugars, have storage and structural roles. Polysaccharides are polymers of hundreds to thousands of monosaccharides joined by glycosidic linkages. Some polysaccharides serve for storage and are hydrolyzed as sugars are needed. Other polysaccharides serve as building materials for the cell or the whole organism. Starch is a storage polysaccharide composed entirely of glucose monomers. Most of these monomers are joined by 1 4 linkages (number 1 carbon to number 4 carbon) between the glucose molecules. The simplest form of starch, amylose, is unbranched and forms a helix. Branched forms such as amylopectin are more complex. Plants store surplus glucose as starch granules within plastids, including chloroplasts, and withdraw it as needed for energy or carbon. Animals that feed on plants, especially parts rich in starch, have digestive enzymes that can hydrolyze starch to glucose. Animals store glucose in a polysaccharide called glycogen.