Question

Enzyme activity in cells is controlled by which of the following?

I) covalent modifications

II) modulation of expression levels

III) feedback inhibition

IV) allosteric effectors

Select one:

A. I

B. II

C. III

D. III, IV

E. I, II, III, IV

Answer 1

Te correct answer is (D.) III, IV

Explanation.

There are mainly 4 factors which control enzyme activity in cells. These are

• Regulatory molecules. Enzyme activity may be increased or decreased by activator and inhibitor molecules that bind specifically to the enzyme. Allosteric effectors are a part of regulatory molecules
• Cofactors. Many enzymes are only active when bound to non-protein helper molecules known as cofactors.
• Compartmentalization. Storing enzymes in specific compartments can keep them from doing damage or provide the right conditions for activity.
• Feedback inhibition. Key metabolic enzymes are often inhibited by the end product of the pathway they control (feedback inhibition).