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A-level Biology > 2.2 Biological Molecules > Flashcards

2.2 Biological Molecules Flashcards

1
Q

what are polysaccharides?

A

monosaccharides

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2
Q

what are polysaccharides made of one type of monomer called?

A

homopolysaccharides

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3
Q

what are polysaccharides made of more than one type of monomer called?

A

heteropolysacharides

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4
Q

why is glucose a source of energy?

A

it is a reactant in respiration

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5
Q

what happens if you join lots of glucose molecules together?

A

an energy store is created

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6
Q

how to plants store energy?

A

in starch granules in chloroplasts and in membranes

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7
Q

what form do amylose, amylopectin and glycogen take?

A

starch granules

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8
Q

why do glycogen and starch make good stores of monosaccharides?

A
  • they are compact
  • some are branched (more compact) and some are unbranched
  • polysaccharides hold glucose molecules in chains meaning energy can be ‘snipped off’
  • polysaccharides are less soluble meaning they don’t mess with the water potential of the cell
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9
Q

what enzymes are responsible for hydrolysing 1-4 glycosidic bonds?

A

amylase

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10
Q

what enzymes are responsible for catalysing 1-6 glycosidic bonds?

A

glucosidase

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11
Q

what is amylose?

A

a long chain of alpha glucose molecules with an unbranched structure and 1-4 glycosidic bonds

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12
Q

what is the structure of amylose?

A

It coils into a spiral shape with the carboxyl group on carbon 2 making the polysaccharide making the molecule less soluble allowing the hydrogen bonds to maintain the coil’s structure

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13
Q

what bonds hold together the coil shape of amylose?

A

hydrogen bonds

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14
Q

what is amylopectin?

A

a long chain of alpha glucose molecules with 1-4 glycosidic bonds and 1-6 glycosidic bonds which allows it have a branched structure

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15
Q

what is the structure of amylopectin?

A

Like amylose it also has a spiral shape held together with hydrogen bonds with branches emerging from the spiral.

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16
Q

what is glycogen?

A

a long chain of alpha glucose molecules with 1-4 and 1-6 glycosidic bonds

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17
Q

what is the structure of glycogen?

A

the 1-4 glycosidic bonds tend to be smaller than amylopectin and less tendecy to coil. there are also more branches making it more compact and easier for for removal of monomers as there are more ends

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18
Q

how can glucose molecules be ‘snipped off’

A

by hydrolysis which is catalysed by enzymes

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19
Q

what do carbohydrates contain?

A

carbon, hydrogen, oxygen

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20
Q

what is meant by a hydrated cabron?

A

two hydrogen atoms and one oxygen atoms for every carbon

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21
Q

what are the 3 functions of carbohydrates?

A

store of energy
source of energy
structural units

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22
Q

what are the three main groups of carbohydrates?

A

monosaccharides
polysaccharides
disaccharides

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23
Q

why are monosaccharides important in living things?

A

they are a source of energy

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24
Q

why are monosaccharides well suited to the role of sources of energy?

A

have a large number of carbon-hydrogen bonds

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25
Q

what are features of monosaccharides?

A

taste sweet
soluble in water
insoluble in non-polar solvents

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26
Q

what form do monosaccharides take?

A

straight chains, in ring or in cylic forms

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27
Q

what are common disaccharides?

A

maltose (malt sugar)
sucrose
lactose (milk sugar)

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28
Q

what kind of sugars are maltose and lactose?

A

reducing sugars

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29
Q

what kind of sugar is sucrose?

A

non-reducing sugars

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30
Q

what is the makeup of maltose?

A

alpha glucose + alpha glucose

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31
Q

what is the makeup of sucrose?

A

alpha glucose + fructose

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32
Q

what is the makeup of lactose?

A

beta galactose + alpha glucose

33
Q

how are glycosidic bonds formed?

A

a condensation reaction reaction

34
Q

how does the condensation reaction form in disaccharides?

A

two hydroxyl groups line up next to each other from which a water molecule is removed

35
Q

how are disaccharides broken into monosaccharides?

A

a hydrolysis reaction - water is added to form a hydroxyl group and a hydrogen

36
Q

what is the role of alpha glucose in the body?

A
  • energy source

- component of starch and glycogen which act as energy stores

37
Q

what is the role of beta glucose?

A
  • energy source

- component of cellulose which act as structural support in plant cell walls

38
Q

what is the role of ribose?

A
  • component of rna, atp and nad
39
Q

what is the role of deoxyribose?

A

component of DNA

40
Q

where is cellulose found?

A

in plant cell walls

41
Q

what is cellulose/what is it made out of?

A

a homopolysaccharide made from long chains of beta glucose led side by side

42
Q

how is cellulose bonded?

A

condensation reaction

43
Q

why is the structure of cellulose a straight line?

A

due to bonding

  • hydrogen and hydroxyl groups on carbon 1 are inverted (every other beta glucose in the chain is rotated by 180 degrees)
  • hydrogen bonds between the rotated molecules give extra strength
  • the hydroxyl groups on carbon 2 stick out enabling the hydrogen bonds to be formed between chains
44
Q

what happens when 60-70 cellulose chains are formed together?

A

microfibrils are formed

45
Q

what happens when microfibrils are bundled together?

A

macrofibrils which are embedded in pectins to form plant cell walls

46
Q

what is pectin?

A

glue

47
Q

why is cellulose a good material for plant cell walls?

A

micro/macrofibrils have high tensile strength due to glycosidic bonds and hydrogen bonds between chains
macrofibrils run is all directions criss-crossing each other
difficult to digest due to glycosidic bonds

48
Q

what do lipids contain?

A

large amounts of carbon and hydrogen but small amounts of oxygen?

49
Q

why are lipids insoluble in water?

A

are not polar and do not attract water molecules

50
Q

what are lipids soluble in?

A

alcohol

51
Q

what are the three most important lipids?

A

triglycerides
phospholipids
steroids

52
Q

what are lipids examples of?

A

macromolecules

53
Q

what are triglycerides made up of?

A

glycerol and 3 fatty acids

54
Q

what is glycerol made of?

A

3 carbon atoms

55
Q

what is glycerol and what does it mean?

A

glycerol is an alcohol meaning it has free -OH groups (3 of them)

56
Q

what are fatty acids made of?

A

they have a carboxyl group attached to a hydrogen group

the carboxyl group ionises into a h+ and a -COO- group meaning it is an acid

57
Q

what does it mean if a fatty acid is saturated?

A

no C=C bonds

58
Q

what does it mean if a fatty acid is unsaturated?

A

there’s double bonds between carbon atoms

59
Q

what does it mean if a fatty acid is monounsaturated?

A

there’s a singular double bond between carbon atoms

60
Q

how does having one or more double bond between change the hydrocarbon?

A

it gives it a kink pushing the molecules apart slightly making the fatty acid more fluid

61
Q

how are triglycerides bonded?

A

ester bonds through a condensation reaction between the -COOH group of the fatty acid and the -OH group of the glycerol.

62
Q

what are the functions of triglycerides?

A 
energy source 
energy store
insulation
buoyancy
protection
63
Q

what is the structure of a phospolipid?

A

same as a triglyceride however one fatty acid is replaced by a phosphate group
a condensation reaction between a OH group on a phospheric acid molecule and one of the three -OH groups on the glycerol to form an ester bond

64
Q

what are the fatty acids in the phospholipid commonly like?

A

there are normally an even number of carbon atoms and one of these chains is generally saturated and one unsaturated

65
Q

what is a phospholipid like in water?

A

it has a negative charge making it polar however the fatty acid tails are non polar. the head is hydrophilic and the tail is hydrophobic meaning the phospholipid is amphipathic

66
Q

what are the properties of amphipathic phospholipids?

A

form a layer on the surface of the water with heads in the water and tails sticking out
may also form micellles

67
Q

what are micellles?

A

tiny balls with the head with the tails tucked away inside and the heads pointing outwards into the water

68
Q

what are amphipathic phospholipids good at?

A

forming membranes

69
Q

what is cholesterol?

A

a steroid alcohol

70
Q

what is cholesterol made of?

A

four carbon based rings (isoprene units)

71
Q

what are the features of cholesterol?

A

small and hyrdrophobic

72
Q

what is the role of cholesterol?

A

maintain the fluidity of the membrane and preventing it from becoming too stiff or fluid

73
Q

where is cholesterol made in animals?

A

In the liver

74
Q

what steroid hormones are made from cholesterol?

A

testosterone
oestrogen
vitamin D

75
Q

where can steroid hormones pass through membranes?

A

the hydrophobic part

76
Q

what are proteins?

A

large polymers comprised of long chains of amino acids

77
Q

what are the functions of proteins?

A
  • form structural components
  • make up enzymes
  • act as carriers for active transport across membranes
78
Q

how do animals get their amino acids?

A

they ingest and make them

79
Q

what are essential amino acids?

A

amino acids that have to be ingested

A-level Biology (23 decks)

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