- cells get energy from glucose. plants store excess glucose as starch (when a plant needs more glucose for energy, it breaks down starch to release the glucose). starch is a mixture of two polysaccharides of a-glucose, amylose and amylopectin :

amylose is a long, unbranched chain of a-glucose. the angles of the glycosidic bonds give it a coiled structure, almost like a cylinder. this makes it compact, so it's really good for storage because you can fir more into a small space.
amylopectin is a long, branched chain of a-glucose. its side branches allow the enzymes that break down the molecule to get at the glycosidic bonds easily. this means glucose can be released quickly.

- starch is insoluble in water and doesn't affect water potential so it doesn't cause water to enter the cells by osmosis, which would make them swell. this makes it good for storage.

	Created by izzy smith about 7 years ago

A level Biology (topic 1a : biological molecules) Slide Set on polysaccharides, created by izzy smith on 01/05/2017.