Explore how reversible binding at an enzyme active site reduces substrate access, and why increasing substrate concentration can lessen competitive inhibition in IB Biology HL C1.1.15.
Interactions in biological systems may have harmful or beneficial effects.
Explain, using an example, how competitive inhibitors interfere with enzyme activity.
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.
4
max