Question

The toxic cyanide anion (CN-) binds to cytochrome c oxidase and prevents electron transfer. Dosing of BP-CML cells with cyanide would result in: I. increased oxygen demand. II. reduced intracellular ATP. III. apoptosis or necrosis.
A. I only
B. I and II only
C. II and III only
D. I, II, and III

Answer 1

Answer: C. Ii & III are correct

II. reduced intracellular ATP.

III. apoptosis or necrosis.

Explanation:

Cytochrome c oxidase controls the last step of food oxidation. Cytochrome c oxidase is an enzyme responsible for electron transfer in the electron transport chain (ETC), it inhibit in slowing down or stopping the ETC.

Consequently, ATP production would be gradually reduced, as the ETC is responsible for the majority of ATP production. This shows option II is correct.

The question starts by stating that cyanide is highly toxic, so this match up with the fact that a large dose would also cause cell death (apoptosis or necrosis). Therefore, option III is also accurate.

Option I: Inhibiting the ETC is consequential as it reduces oxygen demand because electrons would not flow to oxygen, the final electron acceptor.