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Biology - mr stonehouse > module 2 - 2.1.4 enzymes > Flashcards

module 2 - 2.1.4 enzymes Flashcards

1
Q

what are enzymes?

A

biological catalysts

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2
Q

how does the enzyme molecule bind to the active site?

A

collisions between enzyme and substrate

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3
Q

what happens to the product molecules?

A

diffuse away from the active site

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4
Q

what is the most important function of proteins?

A

catalysis

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5
Q

what happens in the absence of catalysis?

A

reactions in biological systems would happen far too slowly to provide products at a good pace for metabolising organisms

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6
Q

where do catalysts serve their function?

A

living organisms called enzymes

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7
Q

what type of proteins are enzymes?

A

globular proteins

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8
Q

what can enzymes increase the rate of reaction up by a factor of?

A

10^20 over uncatalysed reactions

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9
Q

in an enzyme-catalysed reaction, what does the enzyme bind to?

A

substrate to form a complex

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10
Q

what does the lock and key model propose?

A

the substrate binds to the active site which fits exactly

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11
Q

what are some characteristics of enzymes?

A
  • they are proteins of high molecular weight
  • they are biological catalysts
  • sensitive to temperatures, pH and concentration
  • generally specific in reactions they catalyse
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12
Q

what happens at the active site?

A

chemical reactions take place

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13
Q

what happens if the temperature is not controlled?

A

if temp is too low, chemical reactions happen and a slower rate, is temp is too high, it can cause the enzyme to denature and therefore not fit with the substrate

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14
Q

what does it mean when enzymes are of a ‘high molecular weight’?

A

contain lots of amino acids

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15
Q

what is the induced fit model?

A

model that takes into account the fact that proteins (enzymes) have some three-dimensional flexibility

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16
Q

what happens to the enzyme in the induced fit model?

A

binding of the substrate induced the enzyme to change shape and form an exact fit

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17
Q

according to the induced fit model, when can reactions take place?

A

after the induced fit has occurred

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18
Q

why are enzymes catalysts?

A

they lower the activation energy needed to drive a reaction

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19
Q

what do substrates need to overcome before they convert to products?

A

an energy barrier

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20
Q

what happens in relation to molecular collisions at low temperatures?

A
  • molecules are constantly in motion and colliding with one another
  • the speed of motion and number of collisions is affected by temperature (slower - less energy)
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21
Q

what happens in relation to molecular collisions at high temperatures?

A
  • more enzyme-substrate complexes
  • more product molecules are formed at higher temperatures
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22
Q

what temperature is the maximum rate of reaction reached?

A

between 37°C to 40°C
this is called the optimum temperature

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23
Q

what happens when the temperature increases beyond the optimum?

A
  • the bonds that stabalise the enzyme’s secondary and tertiary structure are broken
  • enzyme loses shape (denatures) and can no longer bind to the active site
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24
Q

why is the optimum temperature (37°C to 40°C) not true for all enzymes?

A
  • some bacteria are extremophiles/ thermophiles that are thermostable and so can survive in high temperatures
  • optimum temp is 80°C
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25
Q

what is an example of a thermophile/ extremophile?

A

bacteria that live in hot geysers

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26
Q

which bonds stay together when an enzyme has denatured?

A

the peptide bonds

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27
Q

what is Q10?

A

the reaction rates doubles for every 10°C rise in temperature

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28
Q

when does Q10 occur?

A

in the temperature range from 4°C to 40°C

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29
Q

what does Q10 equal when it doubles every 10°C?

A

Q10 = 2

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30
Q

what happens to the product when there is low substrate concentration?

A

low product concentration per unit time

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31
Q

what happens to the product when there is an increased substrate concentration?

A

more product formed, increased reaction rate

32
Q

how is the acidity of a solution measured?

A

measured by the concentration of hydrogen ions (H+) and is expressed in terms of pH

33
Q

what are the specific conditions that an enzyme can work in?

A
  • particular range of pH
  • each enzyme has its own optimum pH where the rate of reaction is maximum
34
Q

what do the effects of pH on the rate of enzyme controlled reactions display characteristically on a graph?

A

bell shaped curves

35
Q

what can a change in pH affect?

A

can affect the ionic and hydrogen bonds that make the specific tertiary structure of enzymes

36
Q

what do extremes of pH result in?

A
  • breaks the hydrogen and ionic bonds
  • denatures the enzyme
37
Q

what does pH stand for?

A

potential hydrogen (ions)

38
Q

what happens to the hydrogen concentration if an acid is added to pure water?

A

hydrogen ion concentration increases

39
Q

what happens to the hydrogen if a base is added to pure water?

A
  • hydrogen ion concentration decreases
  • hydroxyl ion concentration increases
40
Q

what does an acidic solution contain within the solution?

A

H+ ions and one OH- ion

41
Q

what does an alkaline solution contain within the solution?

A

OH- ions and one H+ ion

42
Q

what happens if there is further increase in substrate concentration?

A
  • maximum product formation
  • maximum rate of reaction
43
Q

what happens if there is excess substrate concentration? what is the limiting factor?

A
  • no further increase in product formation
  • maximum reaction rate maintained
  • enzyme concentration is a limiting factor
44
Q

what happens when a reaction reaches V Max.?

A
  • no further increase in reaction rate
  • all active sites of the enzymes are occupied
45
Q

what does it mean if the rate of reaction is directly proportional to the enzyme concentration?

A

as enzyme concentration increases, rate of reaction increases

46
Q

what does the presence of a reversible inhibitor do to the rate of enzyme controlled reactions?

A

inhibitor molecules decrease in the rate of enzyme reactions by reversible combinations

47
Q

what is a competitive inhibitor?

A

when a molecule competes with the normal substrate active site though random collisions (can be reversible)

48
Q

where do reversible inhibitors attach to on the enzyme?

A

attaches to the enzyme at a position away from the active site

49
Q

what happens once the inhibitor has attached to the enzyme away from the active site?

A
  • the substrate molecule can still bond to the active site
  • substrate cannot be converted into product as inhibitor changes shape of active site preventing induced fit
50
Q

what is the effect of competitive inhibitors on enzyme action?

A

low substrate concentration makes the inhibitor compete successfully for the active site
- reduced rate (less substrate molecules converted to products)

51
Q

what happens to the inhibitor when substrate concentration is low?

A

low substrate concentration makes the inhibitor compete successfully for the active site
- reduced rate (less substrate molecules converted to products)

52
Q

what is the effect of competitive inhibitors on enzyme action?

A

to overcome when high concentration of substrate molecules compete successfully for the active sites of enzymes

53
Q

how can the effect of competitive inhibitors be overcome?

A
  • by very high concentrations
  • high temperatures cause the inhibitor to be out-competed
54
Q

what is a non competitive inhibitor?

A
  • the inhibitor works elsewhere
  • substrate molecules not converted when inhibitor molecules are bound to the enzyme
55
Q

what happens at high substrate concentration with non-competitive inhibitors?

A

all active sites are occupied

56
Q

what happens to substrate molecules bound to enzymes with attached inhibitors?

A
  • they are not converted into products
  • maximum reaction rates are never achieved
57
Q

when are substrate molecules converted into product?

A

when there is no inhibitor attached to enzyme

58
Q

what are metabolic pathways?

A

sequences of chemical reactions each controlled by a specific enzyme

59
Q

when is it wasteful for a sequence of chemical reactions to continue?

A

when the end product in being produced at a rate too much for the requirements

60
Q

what are hydrolases?

A

an enzyme that catalyses hydrolysis reactions

61
Q

what is maltOse?

A

a disaccharide consisting of 2 alpha-glucose molecules joined by 1-4 glycosidic bond

62
Q

what is maltAse?

A

a hydrolase enzyme that catalyses the hydrolysis of maltose into 2 glucose molecules

63
Q

what are transferases?

A

enzymes that catalyse reactions that transfer atoms from one molecule to another

64
Q

during cellular respiration, which group is transferred from ATP to glucose?

A

a phosphate group

65
Q

what are oxidoreductases?

A

enzymes that catalyse reactions involving oxidation and reduction

66
Q

what is oxidation?

A
  • addition of oxygen
  • removal of hydrogen atoms
  • removal of electrons
67
Q

what is reduction?

A
  • removal of oxygen
  • addition of hydrogen atoms
  • addition of electrons
68
Q

what are cofactors?

A

non-protein chemical compounds

69
Q

what are cofactors required for?

A
  • ‘helper molecule’
  • required for enzyme activity as catalyst
70
Q

what are holoenzymes?

A

an active enzyme with non protein component (cofactor)

71
Q

what are apoenzymes?

A

an inactive enzyme without its non protein component (no cofactor)

72
Q

what is a coenzyme?

A

small organic molecule that binds with specific enzymes, helping to catalyse a reaction

73
Q

what are the main enzymes used in respiration?

A
  • NAD
  • CoA
  • FAD
74
Q

what are prosthetic groups?

A
  • non protein group combined with a protein
  • tightly bound, specific non polypeptide unit used for biological functions of some proteins
75
Q

what is the catalase formula?

A

2H20 –(catalase)-> 2H2O +O2

Biology - mr stonehouse (60 decks)

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