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

Starch, Glycogen And Cellulose Flashcards

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
What is significant about the chains of amylopectin being long?
It reduced the amount of ends there are making amylopectin harder to break down, making it harder to digest
26
What is significant about starch being insoluble?
It is osmotically inactive
27
What is glycogen?
The main storage polysaccharide in animals
28
What is glycogen a polymer of?
Alpha-glucose
29
How does the structure of glycogen differ to that of amylopectin?
It is branched but has much shorter 1,4 chains and therefore many more branches
30
What is the significance of glycogen being highly branched?
Quick hydrolysis of glucose off of the branches
31
Is energy release quicker in plants or animals?
Animals
32
Why is energy release greater in animals?
They have a higher metabolic demand
33
What similarities to glycogen and amylopectin have?
They are both joined by 1,4-glycosidic bonds with 1,6-glycosidic bonds joining 1-4 linked chains
34
Where is glycogen found in mammals?
Liver and muscles
35
As a result of being a good storage molecule what role does glycogen play in mammals?
Regulates blood glucose levels
36
What is cellulose?
A polymer of beta-glucose
37
How is cellulose arranged?
In long straight chains
38
What is the role of cellulose?
Structural polysaccharide
39
Why is cellulose strong?
- 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
How are cellulose fibres arranged?
In layers, running across each other interwoven with other substances
41
How are chains of glucose linked?
1,4-glycosidic bonds
42
What is cellulose resistant to?
Enzyme hydrolysis?
43
How is cellulose resistant to enzyme hydrolysis?
Hydrogen bonding prevents water entering the molecule
44
Can humans digest cellulose?
No
45
Why can’t humans digest cellulose?
Humans dont produce cellulase
46
What is the significance of cellulose cell walls being strong?
They need to maintain turgidity so that leaves are held in a position to absorb maximum sunlight
47
What is chitin?
A polymer of glucosamine
48
What bonds link the glucosamine monomers?
Beta-1,4-glycosidic links
49
What is the significance of the amino group?
More hydrogen bonding between the chains than in cellulose therefore, chitin is extremely tough

Biology Chapter 1 (AQA) (32 decks)

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