Polysaccharides

Question 1

Monosaccharides definition?

Answer 1

That monomers from which larger carbohydrates are made

Question 2

Polysaccharides definition?

Answer 2

Polymers created by many condensation reactions between many glucose monomers
- glycogen & starch - alpha
- cellulose - beta

Question 3

Starch?

Answer 3

• formed from 2 polymers of a glucose: Amylose & amylopectin
• found in form of starch grains/grains inside plant cells
• function: insoluble energy storage of glucose in plants
• structure: coiled and branched (due to the presence of 1-4 and 1-6 glycosidic bonds)

Question 4

Structure of amylose?

Answer 4

-1-4 glycosidic bonds between monomers
- chains form coiled shape
- Unbranched chain of amylose coils up to make a helix/spiral

Question 5

Structure of amylopectin?

Answer 5

• 1-4 and 1-6 glycosidic bonding between monomers
• branched shape due to 1-6 glycosidic bond

Question 6

Relationship of structure to function for starch and glycogen?

Answer 6

• Starch: Coiled so is compact (a lot can be stored in very little space)
• both: branched so more ends for faster hydrolysis of glucose molecules - to be used in respiration for energy release (larger SA for enzymes)

Question 7

Glycogen?

Answer 7

• formed from a glucose
• found in muscle and liver cells in animal
• Also stood in small granules like starch
• function: Insoluble energy store of glucose in animals
  Structure: (Very similar structure to amylopectin in starch)
• BUT is highly branched - Less 1-4 glycosidic bonds and more 1 - 6

Question 8

Cellulose?

Answer 8

Function: structural role (provides strength) - found in plant cells
- B glucose
- Only one to four glycosidic bonds - creates long straight unbranched chains of B glucose
- Chains lie parallel to each other - then held in place by many H bonds aka a “fibril”
- B glucose: (Small change OH group on C1 causes huge differences in the structure and function)
- Every other glucose molecule is rotated by 180 degrees to allow the glycosidic bonds to form between the beta glucose molecules

Question 9

Relationship of Structure to function of cellulose?

Answer 9

• B glucose chains run parallel to each other & H bonds form between OH groups on adjacent parallel chains - forming cross linkages aka microfibrils
• microfibrils ->H bond together to form macrofibrils -> then H Bond together to form cellulose fibres
• cellulose fibres are what make up the cell walls in plants
• this formation results in cellulose being very strong - providing strength in cell walls
• H Bonds collectively provide strength to cell wall

Question 10

All three are insoluble?

Answer 10

• Doesn’t affect the water potential of cells so osmosis- won’t have excess water moving in or out of cell - burst

Question 11

Function of cellulose in cell walls?

Answer 11

• Provides strength in cell walls
• Prevents plant cells bursting when water enters by osmosis
• Maintains turgidity and rigidity in plant cells and therefore in the whole plant (stems and leaves)
• Maximises surface area for light absorption for photosynthesis