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Biology Chapter 1 (AQA) > Starch, Glycogen And Cellulose > Flashcards

Starch, Glycogen And Cellulose Flashcards

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1
Q

What is starch a polymer of?

A

Alpha-glucose

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2
Q

Where is starch found?

A

In plants

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3
Q

What is starch a mixture of?

A

Amylose and amylopectin

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4
Q

What is the function of starch in plants?

A

Main storage polysaccharide in plants

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5
Q

What bonds join alpha-glucose molecules in amylose?

A

1,4-glycosidic bonds

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6
Q

What structure is formed in amylose?

A

Helix

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7
Q

What bonds are present in the amylose helix?

A

Hydrogen

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8
Q

Why is amylose a good storage compound?

A
  • It’s insoluble in water

- because of the compact shape it allows tight packing

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9
Q

What bonds join alpha-glucose molecules in amylopectin?

A

1,4-glycosidic bonds

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10
Q

In amylopectin what happens every 25 glucose molecules?

A

Adjacent chains are connected by 1,6-glycosidic bonds

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11
Q

What structure does amylopectin have?

A

Branched

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12
Q

What does amylopectin have?

A

Many protruding ends

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13
Q

What can happen to amylopectins many protruding ends?

A

They can be hydrolysed rapidly therefore allowing rapid release of glucose

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14
Q

What is the test for starch?

A

The iodine test

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15
Q

What is the reagent in the test for starch?

A

Iodine

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16
Q

How do you carry out the test for starch?

A

Add 2-3 drops of the iodine

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17
Q

What is a positive result of the test for starch?

A

Black/blue precipitate forms

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18
Q

What is starch digested to?

A

Maltose

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19
Q

What enzymes digest starch?

A

Salivary and pancreatic amylase

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20
Q

In the digestion of starch what bonds do alpha-amylase break?

A

1-4 links randomly

21
Q

In the digestion of starch what bonds do beta-amylase break?

A

Alternative 1-4 links

22
Q

What is maltose digested into?

A

Alpha glucose

23
Q

What enzyme digests maltose?

A

Maltase found in intestinal juices

24
Q

As well as branched, what is significant about the chains of amylopectin?

A

They are long

25
Q

What is significant about the chains of amylopectin being long?

A

It reduced the amount of ends there are making amylopectin harder to break down, making it harder to digest

26
Q

What is significant about starch being insoluble?

A

It is osmotically inactive

27
Q

What is glycogen?

A

The main storage polysaccharide in animals

28
Q

What is glycogen a polymer of?

A

Alpha-glucose

29
Q

How does the structure of glycogen differ to that of amylopectin?

A

It is branched but has much shorter 1,4 chains and therefore many more branches

30
Q

What is the significance of glycogen being highly branched?

A

Quick hydrolysis of glucose off of the branches

31
Q

Is energy release quicker in plants or animals?

A

Animals

32
Q

Why is energy release greater in animals?

A

They have a higher metabolic demand

33
Q

What similarities to glycogen and amylopectin have?

A

They are both joined by 1,4-glycosidic bonds with 1,6-glycosidic bonds joining 1-4 linked chains

34
Q

Where is glycogen found in mammals?

A

Liver and muscles

35
Q

As a result of being a good storage molecule what role does glycogen play in mammals?

A

Regulates blood glucose levels

36
Q

What is cellulose?

A

A polymer of beta-glucose

37
Q

How is cellulose arranged?

A

In long straight chains

38
Q

What is the role of cellulose?

A

Structural polysaccharide

39
Q

Why is cellulose strong?

A
  • has an inverted arrangement of successive glucose molecules meaning that hydrogen bonds
  • the molecules are tightly cross-linked to form microfibrils
  • microfibres form fibres
40
Q

How are cellulose fibres arranged?

A

In layers, running across each other interwoven with other substances

41
Q

How are chains of glucose linked?

A

1,4-glycosidic bonds

42
Q

What is cellulose resistant to?

A

Enzyme hydrolysis?

43
Q

How is cellulose resistant to enzyme hydrolysis?

A

Hydrogen bonding prevents water entering the molecule

44
Q

Can humans digest cellulose?

A

No

45
Q

Why can’t humans digest cellulose?

A

Humans dont produce cellulase

46
Q

What is the significance of cellulose cell walls being strong?

A

They need to maintain turgidity so that leaves are held in a position to absorb maximum sunlight

47
Q

What is chitin?

A

A polymer of glucosamine

48
Q

What bonds link the glucosamine monomers?

A

Beta-1,4-glycosidic links

49
Q

What is the significance of the amino group?

A

More hydrogen bonding between the chains than in cellulose therefore, chitin is extremely tough

Biology Chapter 1 (AQA) (32 decks)

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