Biological Molecules: Polysaccharide Attributes

Question 1

Glycogen uses and structure

Answer 1

• The storage molecule in animals
• A polymer of alpha glucose, mostly joined together by 1,4 glycosidic bonds but also numerous 1,6 glycosidic bonds. This results in a highly branched structure
• Smaller chains and highly branched molecule: a compact, insoluble, large molecule
• Can be easily hydolysed into alpha glucose for respiration to meet greater energy demands. Can’t cross the cell membrane. No effect on water potential so doesn’t cause osmosis of water in or out of the cell

Question 2

Branched attribute (i.e amylopectin)

Answer 2

More ends for fast breakdown/enzyme action

Question 3

Cellulose uses and structure

Answer 3

• Key structural component of plant cell wall
• A polymer of Beta glucose. All bonds are 1,4 glycosidic bonds. To form glycosidic bonds, adjacent glucose molecules are rotated 180 degrees compared to their neighbour. The parallel rows are joined by collective Hydrogen bonds (individual bonds are weak, collective bonds are strong)

Question 4

Insoluble attribute

Answer 4

Doesn’t cause the movement of water in and out of the cell by osmosis as it has no effect on water potential

Question 5

Large attribute

Answer 5

Can’t cross the cell membrane

Question 6

Starch uses and structure

Answer 6

• The storage carbohydrate in plants. Starch is a mixture of two polysaccharides: Amylose and Amylopectin
• Amylose: 1,4 glycosidic bonds = long unbranched chain. The angle of the bond gives it a coiled structure
• Amylopectin: A polymer of alpha glucose. Mostly joined by 1,4 glycosidic bonds with the occasional 1,6 glycosidic bond (creates branches)

Question 7

Polymer of glucose

Answer 7

Can be rapidly broken down to provide glucose for respiration

Question 8

Coiled attribute (i.e amylose)

Answer 8

Makes molecule compact for storage in the cell