2.2.4 carbohydrates 2: polysaccharides as energy stores

Question 1

describe polysaccharides

Answer 1

• polymers of monosaccharides
• hundreds/thousands of monosaccharide monomers bonded

Question 2

what are polysaccharides called made of 1 single monosaccharide

Answer 2

homopolysaccharide

Question 3

what are polysaccharides called made of more than 1 monosaccharide

Answer 3

heteropolysaccharides

Question 4

example of homopolysaccharide

Answer 4

starch

Question 5

example of heteropolysaccharide

Answer 5

hyaluronic acid (in connective tissue)

Question 6

respiration reaction

Answer 6

glucose + oxygen —–> carbon dioxide + water

Question 7

what is the energy released from the respiration reaction used for

Answer 7

to make ATP

Question 8

how do animals/plants store energy

Answer 8

animals = glycogen in muscles & liver
plants = starch (in chloroplasts) & membrane-bound starch grains

Question 9

example of polysaccharide energy store in plants & animals

Answer 9

animals = glycogen
plants = starch

Question 10

what is starch (plants) made up of

Answer 10

• amylose
• amylopectin

Question 11

describe polysaccharides as good energy stores: compact

Answer 11

• glycogen & starch are compact
• don’t occupy lots of space
  (occur as dense granules)

Question 12

describe polysaccharides as good energy stores: chains

Answer 12

• polysaccharides hold glucose molecules in chains
• easily ‘snipped off’ by hydrolysis if required in respiration

Question 13

describe polysaccharides as good energy stores: unbranched/branched

Answer 13

• some chains unbranched (amylose)
• some chains branched (amylopectin & glycogen)
• branched chains = more compact & offer chance for lots of glucose molecules to be ‘snipped’ by hydrolysis at 1 time

Question 14

which enzyme is responsible for hydrolysing 1-4 glycosidic linkages

Answer 14

amylase

Question 15

which enzyme is responsible for hydrolysing 1-6 glycosidic linkages

Answer 15

glucosidase

Question 16

what’s a 1-4 glycosidic linkage

Answer 16

between carbon 1 of one glucose & carbon 4 of another

Question 17

describe polysaccharides as good energy stores: less soluble in water than monosaccharides

Answer 17

• if many glucose molecules dissolved in cytoplasm, water potential would reduce & excess water would diffuse in = disrupt cell
• less soluble due to size & regions which could hydrogen-bond with water are hidden inside molecule
• sometimes amylose molecule may form double helix which presents hydrophobic external surface

Question 18

describe amylose (plants)

Answer 18

• long chain of alpha glucose
• glycosidic bonds between carbon 1 and 4

Question 19

structure of amylose (plants)

Answer 19

• coils into spiral shape
• hydrogen bonds hold spiral in place
• hydroxyl groups on carbon 2 situated on inside of coil = less soluble & hydrogen bonds maintain coil structure

Question 20

describe amylopectin (plants)

Answer 20

• glycosidic bonds between carbon 1 and carbon 4
• branches formed by glycosidic bonds between carbons 1 and 6

Question 21

structure of amylopectin (plants)

Answer 21

• coils into spiral shape
• spiral held by hydrogen bonds
• branches emerge from spiral

Question 22

describe glycogen (animals)

Answer 22

• glycosidic bonds between carbons 1 and 4
• branches formed by glycosidic bonds between carbons 1 and 6

Question 23

structure of glycogen (animals)

Answer 23

• 1-4 bonded chains are smaller than amylopectin = less tendency to coil
• more branches = more compact
• easier to remove monomer units as more ends