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3.1 Biological Molecules (A Level Biology) > 3.1.4.2 Enzymes > Flashcards

3.1.4.2 Enzymes Flashcards

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1
Q

Why enzymes only catalyse 1 specific reaction

A

The active site of the enzyme has a specific tertiary structure that is complementary to the substrate
Only 1 substrate can bind to the active site to form an enzyme substrate complex

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2
Q

Enzymes are biological catalysts that lower the…of the reaction

A

Activation energy

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3
Q

Enzymes are proteins that have a specific…structure

A

Tertiary

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4
Q

The lock and key model (GCSE) is upgraded to the…model at A level

A

Induced fit

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5
Q

Describe the induced fit model (4)

A

Before the reaction the enzyme isn’t complementary to the substrate
Substrate binds to active site of enzyme forming enzyme substrate complex
The active site of the enzyme changes shape slightly to become complementary to the substrate as it binds
This causes bond strain in the substrate
This lowers the activation energy

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6
Q

4 factors that effect rate of enzyme activity

A

Temperature
PH
Enzyme concentration
Substrate concentration

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7
Q

How temperature effects rate of enzyme activity

A

As temperature increases, so does rate of reaction up to the optimum temperature.
This is because the enzymes and substrates have more kinetic energy so are moving faster so there are more successful frequent collisions between the enzymes and substrates so more enzymes substrate complexes are formed

Above optimum temperature, rate of enzyme activity decreases because the enzyme denatures due to the increased kinetic energy breaking the hydrogen/ ionic bonds between the R groups of the amino acids. This changes the tertiary structure of the enzyme’s active site so that it’s no longer complementary to the substrate
So fewer enzyme substrate complexes are formed as the substrate doesn’t fit

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8
Q

Above and below the optimum pH, the rate of enzyme activity is lower because

A

Changes in pH change the charges on the R groups in the active site of the enzyme which affects the binding of the substrate to the active site.
The change in charges of the R groups also affect the hydrogen and ionic bonds that stabilise the tertiary structure leading to denaturation

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9
Q

Changes in pH changes the charges of the…in the active site of the enzyme

A

R groups

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10
Q

Initially, increasing temperature increases the rate of enzyme activity because the substrates and enzymes have more…so move faster

A

Kinetic energy

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11
Q

When the enzymes and substrates have more kinetic energy, they move faster so there are more….collisions

A

Successful frequent

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12
Q

More successful frequent collisions between enzymes and substrates means more…formed

A

Enzyme substrate complexes

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13
Q

Above the optimum temperature, increased kinetic energy breaks the…/…bonds between amino acid R groups. This changes the tertiary structure of the active site so it’s no longer…to the substrate and so fewer…are formed (the enzyme becomes denatured)

A

Hydrogen, ionic
Complementary
Enzyme substrate complexes

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14
Q

When kinetic energy is too high (temperature is above the optimum) the hydrogen and ionic bonds between amino acid R groups are broken so the enzyme denatures and the tertiary structure of the active site changes so the active site is no longer…to the substrate

A

Complementary

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15
Q

If the active site of the enzyme is no longer complementary to the substrate then fewer …can be formed as the substrate doesn’t fit

A

Enzyme substrate complexes

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16
Q

How enzyme concentration effects rate of enzyme activity

A

High enzyme concentration means more successful frequent collisions between enzymes and substrates so more enzyme- substrate complexes formed so there is an increased rate of reaction.

At very high enzyme concentrations, the rate of reaction starts to slow and plateau because the number of enzyme molecules starts to exceed the number of substrate molecules

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17
Q

At very high enzyme concentrations the rate of reaction starts to slow (plateau) because the number of…exceeds the number of…

A

Enzyme molecules
Substrate molecules

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18
Q

How substrate concentration affects rate of enzyme activity

A

As substrate concentration increases, rate of reaction increases because there are more successful frequent collisions between the enzymes and substrates so more enzyme- substrate complexes are formed
However when the substrate concentration becomes very high the enzymes becomes saturated with substrate as all active sites are occupied. This means a further increase in substrate concentration won’t result in any more enzyme substrate complexes being formed and so the reaction proceeds at a maximum rate that cannot be increased unless more enzyme is added

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19
Q

Enzymes only catalyse 1 specific reaction because the active site has a specific …structure that’s complementary to the substrate. This means that only 1 substrate can…to the active site to form an…

A

Tertiary bind
Enzyme- substrate complex

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20
Q

When the substrate binds to the active site, the active site changes shape slightly to become complementary to the substrate which causes bond strain in the substrate and lowers the..

A

Activation energy

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21
Q

A buffer solution should be close to the…pH of the enzyme

A

Optimum

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22
Q

For a product time graph, when the graph reaches a plateau the rate of reaction is …

A

0
(No more product is being formed so no reaction is occurring)

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23
Q

For a substrate- rate graph when the graph plateaus it means that the rate of reaction is…
(Where substrate is substrate concentration and rate is rate of reaction)

A

At its maximum rate

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24
Q

For all enzyme experiments, the control set up (this is different to the control variable) is the…enzyme solution

A

Boiled
(The enzyme is denatured)

25
Q

At a very high substrate concentration, a further increase in concentration won’t result in any more…being formed

A

Enzyme- substrate complexes

26
Q

As part of the induced fit model, when the active site of the enzyme changes shape it causes…in the substrate which lowers the…

A

Bond strain
Activation energy

27
Q

As part of the induced fit model, before…the active site of the enzyme isn’t complementary to the substrate

A

The reaction

28
Q

Inhibitors are substances that…or…interfere with the functioning of the active site of a specific enzyme so decrease rate of reaction

A

Directly (competitive inhibitors as they bind to the active site)
Indirectly (non competitive inhibitors as they bind to the Allosteric site which then changes the shape of the active site)

29
Q

…are substances that directly or indirectly interfere with the active site of a specific enzyme so decrease rate of reaction

A

Inhibitors

30
Q

Inhibitors are substances that directly or indirectly interfere with the….so decrease rate of reaction

A

Functioning of the active site of a specific enzyme

31
Q

Inhibitors… rate of reaction

A

Decrease

32
Q

2 types of inhibition are … and…

A

Competitive
Non competitive

33
Q

…inhibitors are a similar shape to the substrate

A

Competitive

34
Q

Competitive inhibitors are a similar shape to the…

A

Substrate

35
Q

…inhibitors aren’t a similar shape to the substrate so don’t look like the substrate

A

Non competitive

36
Q

…inhibitors bind to the enzyme at the Allosteric site

A

Non competitive

37
Q

Non competitive inhibitors bind to the enzyme at the…site

A

Allestoric

38
Q

…inhibitors bind to the enzyme at the active site

A

Competitive
As they are complementary to the active site (have a similar shape to the substrate)

39
Q

Competitive inhibitors bind to the enzyme at the…site

A

Active

40
Q

Competitive inhibitors have a similar shape to the substrate and are complementary to the active site so bind to the enzyme at the …site
Meanwhile non competitive inhibitors aren’t a similar shape to the substrate or complementary to the active site so bind to the enzyme at the…site

A

Active
Allosteric

41
Q

Inhibitors can either bind to the enzyme at the…site or the…site depending on whether they are competitive or non competitive

A

Active (competitive inhibitors)
Allosteric (non competitive inhibitors)

42
Q

True or false, competitive inhibitors are the same shape as the substrate

A

False
They’re similar shape

43
Q

Competitive inhibitors reduce the number of enzymes substrate complexes that can form by binding to the…

A

Active site

44
Q

competitive inhibitors binds to the active site of the enzyme to form a …complex

A

Enzyme- inhibitor

45
Q

True or false, in competitive inhibition the rate of reaction can still reach its maximum rate

A

True
(If substrate concentration is high enough/ higher than the inhibitor concentration as it means there’s a lower chance of the inhibitor binding to the active site and a higher chance of the substrate binding to the active site so a higher chance of enzyme- substrate complexes being formed)
However the maximum rate will be reached more slowly than it would without the inhibitor

46
Q

For..inhibition the reaction can still reach its maximum rate

A

Competitive
(If substrate concentration is higher enough)

47
Q

For..inhibition the reaction can still reach its maximum rate

A

Competitive
(If substrate concentration is higher enough)

48
Q

Non competitive inhibitors bind to the Allosteric site of the enzyme to form a …complex

A

Enzyme- inhibitor

49
Q

Both competitive and non competitive inhibitors bind to the enzyme to form a…complex

A

Enzyme- inhibitor

(It’s just the site that they bind to that’s different as competitive inhibitors bind to the active site but non competitive inhibitors bind to the Allosteric site)

50
Q

When the non competitive inhibitor binds to the Allosteric site of the enzyme it changes the …/ …of the enzyme

A

Shape of active site
Tertiary structure

(This means that the substrate is no longer complementary so can no longer bind to the active site and fewer enzyme substrate complexes are formed so the rate of reaction decreases)

51
Q

…make the active site of the enzyme more complementary to the substrate so increase rate if reaction (they work in the opposite way to inhibitors)

A

Activators

52
Q

Inhibitors are substances that directly/ indirectly interfere with the…of the active site of a specific enzyme so decrease rate of reaction

A

Functioning

53
Q

Both types of inhibition lead to fewer…being formed

A

Enzyme substrate complexes

54
Q

Term used to describe enzymes that function outside of cells

A

Extracellular

55
Q

Term used to describe an enzyme that functions inside of cells

A

Intracellular

56
Q

Intracellular vs extra cellular enzymes

A

Intracellular enzymes act/ function inside the cell
Extracellular enzymes act/ function outside of the cell

57
Q

True or false, the source of activation energy for the reaction is normally heat

A

True

58
Q

Explain why, in terms of activation energy, an enzyme enables reactions to occur at lower temperatures than without the enzyme

A

Activation energy is needed to start a chemical reaction and often comes in the form of heat. An enzyme lowers the activation energy of the reaction so less heat is needed so the reaction can take place at a lower temperature than it would without the enzyme

3.1 Biological Molecules (A Level Biology) (10 decks)

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