Starch, Cellulose, Glycogen

Question 1

What two polysaccharides make up starch and how do they differ?

Answer 1

Amylose- straight and unbranched chain which forms a coil.
Amylopectin- Long branched chain, side branches allow enzymes that break down the molecule to easily access the glycosidic bonds. (Means glucose released quickly)

Question 2

Name important properties of starch

Answer 2

Insoluble in water and doesn’t affect water potential, so water can’t enter cells(osmosis) and make cell swell. This makes it good for storage.

Question 3

How can you test for starch?

Answer 3

Add Iodine dissolved in potassium iodide solution, if starch is present the sample turns from browny-orange colour to blue-black.

Question 4

Starch is the main …. ….. material in …….

Answer 4

Starch is the main energy storage material in plants.

Question 5

Glycogen is the main ….. ….. material in …….

Answer 5

Glycogen is the main energy storage material in Animals.

Question 6

What are starch and glycogen both polysaccharides of?

Answer 6

Alpha-glucose.

Question 7

Describe the structure of Glycogen

Answer 7

Similar to Amylopectin but more side branches meaning glucose is released quickly (important for energy release in animals).
Also very COMPACT molecule so good for storage.

Question 8

Describe the structure of cellulose

Answer 8

molecules arranged in 180 degree rotations.
H cross linkages=strong
H bonds form microfibrils = structural support for plant cell walls.

Question 9

Describe the structure of starch

Answer 9

Amylose (straight, helical,compact,)glycosidic bonding on Carbons 1-4
Amylopectin (branched )
glycosidic bonding on Carbons 1-4 and 1-6