IB Biology HL 1.1.15 Competitive inhibition Question Bank

a. binds to the active site / inhibitor is complementary to the active site;

b. prevent binding of substrate (so reducing enzyme activity/rate of reaction) OR

fewer enzyme-substrate complexes form;

c. inhibitor chemically similar/similar in shape/similar in structure to substrate

d. statins are competitive inhibitors of HMG-CoA reductase/enzyme needed to make cholesterol;

e. statins prevent conversion of HMG-CoA to mevalonate;

Marking guidance:

Accept other examples for mark point d and mark point e such as:

Oxygen binds to rubisco (d.) and preventing production of glycerate 3-phosphate (e.)

Malonate binds to succinic dehydrogenase (d.), preventing production of fumarate (e.).

Allow penicillin as a competitive inhibitor of transpeptidase/for bacterial cell wall production for mark point d, but not mark point e.

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