1.8- Factors affecting enzyme activity

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  • Created by: Megan2413
  • Created on: 03-10-16 11:37
What four factors affect enzyme activity?
- Temperature - pH - Enzyme concentration - Substrate concentration
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What happens to the rate of reaction as the temperature is increased?
The rate of reaction increases up to a certain point
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Why does the rate of reaction increase as the temperature does (explain using the particle model)
As the temperature increases this increases the amount of energy that the particles have, so they vibrate more. This increases the chance of a collision, and the more energy that a partcile has when it collides, (next flash card)
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Continuation
The more likely that a successful collision will occur, increasing the rate of reaction
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What happens once the temperature has passed its optimum in an enzyme reaction?
The enzyme denatures. It's active site changes shape and the substrate can no longer fit into it hence the reaction can't be catalysed.
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Sketch the graph showing what happens to the rate of reaction as the temperature increases in an enzyme reaction
Page 12 of revision guide
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All enzymes have an _______ pH value
Optimum pH value
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What pH do most human enzymes work best at?
pH 7
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What pH does Pepsin work best at and why?
pH 2 because it is present in the stomach which is acidic
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What happens if an enzyme reaction occurred either above or below the optimum pH value?
Above or below the optimum pH values the H+ and OH- ions can interfere with the ionic and hydrogen bonds that hold the tertiary structure of the enzyme together, hence why they denature and the rate of reaction decreases.
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Sketch a graph showing how the rate of reaction changes as the pH changes in an enzyme reaction (where its optimum pH value is pH 7)
Page 12 of revision guide
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How does the enzyme concentration affect the rate of reaction?
The more enzyme molecules there are the more likely a substrate molecule will collide with one and form an enzyme-substrate complex, hence as the enzyme concentration increases so does the rate of reaction, up to a certain point
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Why does the rate of reaction only increase up to a certain point?
The enzyme concentration may no longer be the limiting factor. If the amount of substrate is limited there comes a point where there's more enzymes than substrate, so it has no further affect
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Sketch a graph showing how the rate of reaction changes as the concentration of enzymes increases
Page 12 of revision guide
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The higher the substrate concentration, the ______the reaction up to a certain point
Faster
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Why does the rate of reaction increase as the concentration of substrate increases?
The more substrate molecules there are, the more likely that a collision will occur with the enzymes
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Why does the rate of reaction only increase up to a certain point?
If all the active sites of the enzyme molecules are full, then adding more substrate will add no further affect as there are no more enzymes to catalyse the substrates
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What are the two ways that enzyme activity can be inhibited?
Competitive inhibition and non-competitive inhibition
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What happens during competitive inhibition?
Competitive inhibitor molecules have a similiar shape to the substrate, and they bind ot the active site of an enzyme so that no reaction can take place in that enzyme as they block it so no substrate molecules can fit in
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Draw a diagram to show how competitive inhibitors work
Page 13 of revision guide
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How much the enzyme is inhibited depends on the r_______ c_____________ of the inhibitor to the s________
relative concentrations - substrate
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If there's a high concentration of inhibitors...
Most of the enzyme active sites will be used up and hardly any substarte will be catalysed
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How can the inhibitor action be decreased?
By increasing the concentration of substrate
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How do non-competitive inhibitors work?
Non-competitive inhibitor molecules bind to another part of the enzyme other than the active site which causes the active site of the enzyme to denature and change shape. So for the rest of the reaction that enzyme can no longer catalyse the reaction
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Are the non-competitive inhibitors a similar shape to he substrate molecules?
No
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Will increasing the concentration substrate make any difference to the rate of reaction whne non-competitive inhibitors are involved?
No
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Draw a diagram to show how non-competitive inhibitors work
Page 13
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Other cards in this set

Card 2

Front

What happens to the rate of reaction as the temperature is increased?

Back

The rate of reaction increases up to a certain point

Card 3

Front

Why does the rate of reaction increase as the temperature does (explain using the particle model)

Back

Preview of the front of card 3

Card 4

Front

Continuation

Back

Preview of the front of card 4

Card 5

Front

What happens once the temperature has passed its optimum in an enzyme reaction?

Back

Preview of the front of card 5
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