Enzymes at work - inhibitors of action

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  • Created by: racheon
  • Created on: 24-03-14 18:34
Define inhibitors.
Substances or molecules that slow down the rate of an enzyme-controlled reaction by affecting the enzyme molecule.
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A wide range of inhibitors exist, but there are 2 main types. What do they do?
Affect the active site or affect another part of the enzyme which indirectly causes a change in the shape of the active site.
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What do competitive inhibitors have a similar shape to, and what does this mean they can do?
Substrate molecules, which means they can occupy the active site and form enzyme-inhibitor complexes.
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What don't enzyme-inhibitor complexes lead to and why?
The formation of products because the inhibitor isn't identical to the substrate so the enzyme doesn't catalyse a reaction.
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Why does enzyme inhibition due to competitive inhibitors occur?
Because when a inhibitor is occupying an active site a substrate molecule can't enter, so the number of enzyme-substrate complexes is reduced and the reaction rate slows down.
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What does the level of inhibition depend on when talking about competitive inhibitrs?
The concentration of inhibitor and substrate.
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Where the numbers of substrate molecules are increased what happens to the level of inhibition caused by competitive inhibitors and why?
It decreases because a substrate molecule is more likely to collide with an active site.
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Why are non-competitive inhibitors different to competitive inhibitors?
They don't compete with substrate molecules for the active site, they attach to the enzyme in a different region.
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What do non-competitive inhibitors do to the enzyme molecule?
They distort it's tertiary structure which leads to a change in the shape of the active site.
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What happens if the active site of an enzyme molecule is changed?
The substrate doesn't fit into it, so enzyme-substrate complexes can't form and the reaction rate decreases.
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What does the level of inhibition due to non-competitive inhibitors depend on?
The number of inhibitor molecules.
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If there are enough non-competitive molecules to bind to all the enzyme molecules what will happen?
The reaction will stop.
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What will changing the substrate concentration do to a mixture where all the enzymes are bound to non-competitive inhibitors?
It will have no effect.
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How long do most competitive inhibitors bind to an enzyme molecule?
For a short period of time then they leave, they don't bind permanently.
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Is the action of competitive inhibitors reversible or irreversible and why?
It's reversible as removal of the inhibitor from the reacting mixture leaves the enzyme unaffected.
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How long do many non-competitive inhibitors bind to an enzyme molecule?
They bind permanently to the enzyme molecule
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Is the action of non-competitive inhibitors reversible or irreversible and what effect does this have?
It's irreversible, and any enzyme molecules bound by and inhibitor are effectively denatured.
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What human process is regulated by the inhibition of enzymes and why?
A number of metabolic pathways because they control reaction rates.
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What should you not assume about non-competitive inhibition?
That it is reversible.
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What are reversible non-competitive inhibitors used for and how do they do this?
They're vital to controlling metabolic functions by regulating enzyme activity in cells.
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Other cards in this set

Card 2

Front

A wide range of inhibitors exist, but there are 2 main types. What do they do?

Back

Affect the active site or affect another part of the enzyme which indirectly causes a change in the shape of the active site.

Card 3

Front

What do competitive inhibitors have a similar shape to, and what does this mean they can do?

Back

Preview of the front of card 3

Card 4

Front

What don't enzyme-inhibitor complexes lead to and why?

Back

Preview of the front of card 4

Card 5

Front

Why does enzyme inhibition due to competitive inhibitors occur?

Back

Preview of the front of card 5
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