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Mutations and enzyme function
A mutation is a change in a gene. People who have AKU have a mutation that causes the production of a non-functioning enzyme. Enzymes are proteins.
Suggest how a mutation can result in the production of a non-functioning enzyme.
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Marking points
- 1 Links the mutation to a changed/incorrect amino-acid sequence.
- 2 Links that sequence change to a different enzyme or active-site shape and hence loss of function.
Full-mark answer
The mutation changes the amino-acid sequence of the enzyme. This changes the shape of the enzyme’s active site, so its substrate no longer binds and the enzyme does not function.
Why this answer loses marks
The mutation denatures the enzyme.
Denaturation is not credited here; trace the mutation through the amino-acid sequence to a changed active-site shape.