3.1.2.4 Polysaccharides structure and function and the starch test Flashcards

1
Q

How is the structure of cellulose suited to its function?

A
  • β-Glucose molecules can form long straight chains
  • Parallel chains of cellulose form hydrogen bond ‘cross links’ which add strength
  • Cellulose is arranged into microfibrils and then fibres, which add yet more strength
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2
Q

Which type of bond forms between adjacent α-glucose molecules in glycogen?

A

α 1-4 glycosidic bonds

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3
Q

Unbranched starch (amylose) coils into a…

A

compact helix structure

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4
Q

What test is described below:

Place 2 cm3 of the sample being tested into a test tube

Add 2 drops of iodine solution

A blue black colouration indicates a positive result

A

The test for starch

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5
Q

Identify the polysaccharide

A

Starch (amylose)

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6
Q

Identify the polysaccharide

A

Starch (amylopectin)

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7
Q

What form does starch take within plant cells?

A

Starch grains

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8
Q

Which type of bond forms between branching α-glucose molecules in glycogen?

A

α 1-6 glycosidic bonds

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9
Q

Which type of bond forms between unbranched starch (amylose) molecules?

A

α 1-4 glycosidic bonds

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10
Q

Identify the polysaccharide

A

Cellulose

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11
Q

How is glycogen different to starch?

A

Glycogen has many more branches

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12
Q

Identify the polysaccharide

A

Glycogen (more branches than starch)

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13
Q

Which type of organism contains starch?

A

Plants

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14
Q

What form does glycogen take in cells?

A

granules within muscle and liver cells

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15
Q

What type of reaction occurs when monosaccharides join?

A

Condensation reaction

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16
Q

How would you test for starch?

A
  1. Place 2 cm3 of the sample being tested into a test tube
  2. Add 2 drops of iodine solution
  3. A blue black colouration indicates a positive result
17
Q

Cellulose microfibrils are grouped are arranged in parallel groups called…

18
Q

Which monosaccharide is cellulose made from?

A

β-Glucose

19
Q

How does the structure of glycogen make it suited to its function?

A
  • It is insoluble so does not cause water to move into the cell via osmosis
  • It is large so does not diffuse out of animal cells
  • It is compact
  • It forms α-Glucose when hydrolysed for respiration
  • Many more branches than starch allow α-Glucose to be released faster from glycogen
21
Q

What is the function of glycogen?

A

an energy store for animal and bacterial cells

22
Q

The coiled helix structure of unbranched starch (amylose) is held in place by…

A

hydrogen bonds

23
Q

What is the function of cellulose?

A
  • Cellulose is a major component of plant cell walls and provides rigidity to plant cells
  • Stops plant cells bursting when water enters
24
Q

How are parallel chains of cellulose held together?

A

hydrogen bonds

25
Q

What structure does cellulose take?

A

Long unbranched chains that run parallel to each other

26
Which type of bond forms between branched starch (amylopectin) molecules?
α 1-6 glycosidic bonds
27
Which type of monosaccharide is starch made from?
α-Glucose
28
Which type of bonds join β-Glucose molecules when they form cellulose?
β 1-4 glycosidic bonds
29
Cellulose chains are arranged in parallel groups called....
microfibrils
30
Why does glycogen require more branches than starch?
Animal cells require more energy to function
31
How does the structure of starch make it suited to its function?
* It is insoluble so does not cause water to move into the cell via osmosis * It is large so does not diffuse out of plant cells * It is compact * It forms α-Glucose when hydrolysed for respiration * Many branches allow α-Glucose to be released fast
32
Name the 3 types of polysaccharide
Starch (amylose and amylopectin) Glycogen Cellulose
33
What is the main function of starch?
energy storage in plant cells
34
Describe the structure of glycogen
POLYMER of alpha glucose joined by glycosidic bonds branched structure
35
How does glycogen act as a source of energy?
branched chains are HYDROLYSED into glucose used in respiration
36
Which type of monosaccharide is glycogen made from?
α-Glucose