Antimycin A
(I)inhibition can be restored by addition of succinate.
(II)inhibition can be restored by addition of cytochrome c.
(III)blocks consumption of oxygen.
(IV)blocks transfer of electrons from CoQ to Complex III.
A)I,II,III,IV
B)I,II,III
C)II,III,IV
D)II,III
E)III only

Question

Quizplus · Accepted Answer

Antimycin A blocks transfer of electrons from CoQ to Complex III, which means that electrons cannot be transferred to cytochrome c. Therefore, addition of cytochrome c cannot restore inhibition. However, inhibition can be restored by addition of succinate, which allows electrons to be directly added to Complex II and bypass Complex III. Antimycin A also blocks consumption of oxygen, which is a consequence of the blockage in electron transfer. Therefore, choices II, III, and IV are correct, while choice I is incorrect. Thus, the best choice is C.

Antimycin a (I)inhibition Can Be Restored by Addition of Succinate