starch (structure to function)

Question 1

starch:

Answer 1

amylose and amylopectin

Question 2

composed of several hundred thousands of alpha glucose molecules monomers linked by alpha 1-4 glycosidic bonds

Answer 2

• stores large amount of energy –> glucose is the main respiratory substrate

Question 3

amylose chains are helicial in shape

Answer 3

compact and ideal for storage

Question 4

amylopectin are highly branched due to alpha 1-6 glycosidic bonds

Answer 4

• compact, ideal for storage
• easily converted to sugars by hydrolysis as the branched, porous structure allows attack by enzymes
• debranching enzymes can digest alpha 1-6 glycosidic bonds, further increasing the rate of hydrolysis

Question 5

structure for amylose

Answer 5

• unbranched helical chin with 6 glucose residues for every complete turn of the helix
• chain coils helically as a result of intra-chain H bonding between hydroxyl groups, resulting in a more compact shape

Question 6

large molecule with OH group occupied in intrachain H-bonding

Answer 6

insoluble, therefore osmotically inactive
- will not affect osmotic concentration in cells –> water cannot be absorbed into the cells and the cells will not swell

Question 7

structure of amylopectin

Answer 7

• helical chain which are highly branched and thus more compact
• glucose residues along the helical chains are linked by alpha (1-4) glycosidic bonds
• branch points are formed by alpha (1-6) glycosidic bonds
  the many branch ends allow a number of enzymes to act on it at any one time so it can be easily broken down

Question 8

starch’s solubility

Answer 8

insolube in water due to
1. bulky size
2. many OH groups are protected within the helical regions of the molecule and are unavailable for water molecules to H-bond with