Starch, glycogen + cellulose (specific polysaccharides) Flashcards

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1
Q

Describe the structure of starch

A
  • made up of chains of alpha-glucose (formed by condensation reactions)
  • chains can be branched or unbranched
  • unbranched chain: wound into a tight coil which make the molecule very compact
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2
Q

Name two types of starch

A

Amylose

Amylopectin

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3
Q

Describe the function of starch

A
  • Forms an important component in food
  • The major energy source in most diets
  • Energy storage
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4
Q

Describe the role of structure in the function of starch (energy storage)

A

Insoluble so doesn’t affect water potential - means water is not drawn into cells by osmosis
Large + insoluble - doesn’t diffuse out of cells
Compact - lots can be stored in a small space
When hydrolysed forms alpha-glucose - means it’s easily transported + readily used in respiration
Branched form has many ends - so can be acted on by enzymes simultaneously meaning glucose monomers are released very rapidly

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5
Q

State where starch is found (type of cells)

A

only found in plants cells

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6
Q

Describe the structure of glycogen

A
  • Very similar to starch but has shorter chains + more highly branched
  • In animals stored as small granules mainly in the nucleus + liver
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7
Q

Describe the function of glycogen

A
  • Major carbohydrate storage product of animals

- Mass of carbohydrate stored is relatively small as fast is the main storage molecule in animals

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8
Q

Describe the role of the structure in the function of glycogen (storage)

A

Insoluble - so doesn’t tend to draw water into cells by osmosis
Insoluble - doesn’t diffuse out of cells
Compact - lots can be stored in a small space
More highly branched than starch so has more ends that can be acted on simultaneously by enzymes so rapidly broken down to form glucose monomers used in respiration - important to animals with high metabolic + respiratory rate than plants (as they’re more active)

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9
Q

Draw a simple diagram of starch/glycogen structure (same but glycogen has shorter chains + more highly branched) and a quick description

A

a-glucose unbranched helical chain

The OH groups pointing inwards form the hydrogen bonds it holds the helix chain in place

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10
Q

Describe the function of cellulose

A
  • Major component of plant cell walls + provide rigidity to plant cell
  • Cellulose cell wall prevents cell from bursting as water enters it by osmosis (exerts inward pressure that stops anymore influx of water
  • turgid plant cells push against one another + makes the plant semi-rigid - important to maintaining stems +leaves in turgid state to provide max. surface area for photosynthesis
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11
Q

Describe the role of structure in the function of cellulose (support + rigidity)

A
  • The molecules are made up of B-glucose so form long, straight + unbranched chains
  • Cellulose molecular chains run parallel to each other + are cross-linked by H bonds which add collective strength
  • Molecules are grouped to form microfibrils which are grouped to from fibres + provides yet more strength
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12
Q

State where glycogen is found (type of cells)

A

Animal and bacteria cells

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13
Q

State where cellulose is found (type of cells)

A

Plant cells

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14
Q

Draw a simple diagram of cellulose with a quick description

A

Cellulose molecules composed of B-glucose molecules

Microfibrils made up of cellulose molecules

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