2.9.3 Feedback Inhibition and Cooperativity

Question 1

feedback inhibition

Answer 1

• a type of enzyme regulation that involves the inhibition of an enzyme in a metabolic pathway by an end product of that metabolic pathway. Feedback
  inhibition can also take place in regulatory pathways of hormones.
• Metabolic pathways are the processes that lead to the construction or destruction of molecules. Precursor molecules will be transformed, in steps, to the end product. An enzyme mediates each step.
• In this hypothetical pathway, D is the end product. If D accumulates, it will inhibit enzyme X. Enzyme X converts A to B. Without enzyme X, B will not be produced, and the pathway will not be able to continue.

Question 2

cooperativity

Answer 2

• an enzyme regulatory mechanism that involves multi-subunit enzymes. The binding of a substrate molecule to one subunit enhances the other subunits’ ability to
  bind to substrate

Question 3

Feedback inhibition, or negative feedback, results in levels of product that

Answer 3

• oscillate around an optimal level

Question 4

A(n) __________ is any molecule that binds with an enzyme to down-regulate catalysis

Answer 4

• inhibitor

Question 5

True or false?

Feedback inhibition increases the rate of production of enzymatic product

Answer 5

• false

Question 6

Which of the following statements adequately describes cooperativity?

a. The binding of an activator to one subunit stabilizes the active state.
b. The binding of an inhibitor to one subunit stabilizes the inactive state.
c. The binding of a substrate molecule to a subunit stabilizes the active state of other subunits.
d. None of the above

Answer 6

• c. The binding of a substrate molecule to a subunit stabilizes the active state of other subunits