1.3 Carbohydrates (Polysaccharides)

Question 1

What are the three main Polysaccharides?

Answer 1

Starch, cellulose (plants), glycogen (animals)

Question 2

What are polyssaccharides good for and why? (4)

Answer 2

Starch and glycogen are energy storage molecules within cells.

1. Compact molecules
2. Low solubility in water.
3. Do not affect the concentration of water in the cytoplasm
4. do not affect movement of water into or out of the cell by osmosis.

Question 3

What is starch a mixture of? Storage molecule in plants.

Answer 3

Two molecules: Amylose and Amylopectin.

Question 4

Amylose

Answer 4

Straight chain of glucose molecules with 1,4 glycosidic links between the glucose molecules.
Position of bonds causes the chain to coil into a spiral shape.
Alpha glucose form tight spirals therefore it is compact.
Insoluble, no osmotic effect.

Question 5

Amylopectin

Answer 5

Amylopectin is a polymer of glucose but it has side branches.
1,6 glycosidic link holds each side branch onto the main chain.
Insoluble, no osmotic effect.
Lots of branches and digested more rapidly

Question 6

What does Bacteria, Fungi and animals store?

Answer 6

Glycogen instead of starch.

Question 7

Glycogen

Answer 7

Glycogen is another polymer composed of glucose molecules.
Numerous side branches means that it can be rapidly hydrolyzed, giving easy access to stored energy.
Glycogen in humans is stored in muscles and the liver.

Question 8

Cellulose

Answer 8

Cellulose is know as the dietary fiber and is a non-starch polysaccaride.
Glucose molecules form a straight chain with no branches.

Indigestible in the human gut, cellulose has an important function in the movement of material through the digestive tract.