1.4- Starch glycogen and cellulose

Question 1

Describe the structure of starch

Answer 1

Chains of alpha glucose monosaccharides linked together by glycosidic bonds formed by condensation reactions
1,4 and 1,6 linkages

Question 2

How does starch’s structure relate to it’s function?

Answer 2

1. Insoulable- doesn’t affect water potential so water isn’t drawn into the cells by osmosis. Doesn’t diffuse out of cells
2. Helical-compact and a lot can be stored in a small space
3. When hydrolysed it forms alpha glucose which can be easily transported and is readily used in respiration
4. The branched form has many ends which enzymes can act on simultaneously meaning that glucose monomers are released rapidly

Question 3

What is the function of starch?

Answer 3

Energy storage molecule found in plants

Question 4

Describe the function of glycogen

Answer 4

Energy storage molecule found in animal cells

Question 5

Describe the structure of glycogen

Answer 5

Alpha glucose monosaccharides joined together by glycosidic bonds formed by condensation reactions
Highly branched and shorter chains that starch

Question 6

How does the structure of glycogen relate to its function?

Answer 6

1.Insoluable- doesn’t affect water potential so water isn’t drawn into cells by osmosis. Doesn’t diffuse out of cells
2. Compact- a lot can be stored in a small space
3. Highly branched so has a lot of ends that can be acted on simultaneously by enzymes. Can be quickly hydrolysed to form glucose monomers which are used respiration. This is important in animals that have a high metabolic and respiratory rate.

Question 7

Describe the function of cellulose

Answer 7

1.A major component of plant cell walls
2. Prevents the cell from bursting as water enters by osmosis by providing mechanical support

Question 8

Describe the structure of cellulose

Answer 8

Straight unbranched chains of beta glucose
Hydrogen bonds form between adjacent chains
Each successive beta glucose unit is rotated 180
1,4 linkages

Question 9

How does the structure of cellulose relate to its function?

Answer 9

Beta glucose monomers form long unbranched straight chains. Chains run parallel to each other and are linked by hydrogen bonds which add collective strength. These molecules are grouped to form microfibrils which provide strength for the cell wall