Starch, cellulose, dextran, and glycogen are polysaccharides. How are they similar? To what are their different properties due? Why can't an enzyme that hydrolyzes starch degrade cellulose?

similarity

Starch, cellulose, dextran and glycogen are all polymers of glucose

differences

monomer/glucose glycosidic bond branching

1. starch α glucose 1-4 and 1-6 branch and unbranced

amylose 1-4 unbranched

amylopectin 1-4 and 1-6 branched

2. dextran α glucose 1-6 branched

3. cellulose β glucose 1-4 unbranched, linear

4. glycogen α glucose 1-4 and 1-6 branched (shorter

branches than starch)

Enzyme: amlase acts on starch and cellulase acts on cellulose as they are specific for their substrates.

Explanation:

Starch: Consists of both branched amylopectin and unbranched amylose

Enzymes: Enzymes are specific as the gulcose molecule in starch is α and in cellulose is β which differ in their position of hydroxyl groups at anomeric carbon, their structures differ so they form different bonds. Active sites of enzymes can act only on specific bonds a sthey can fit to their specific substrates.