Question

The electron transport chain is a series of redox reactions that result in ATP synthesis. Which of the following is a cytochrome complex IV inhibitor?

• A. Cyanide
• B. Carbon dioxide
• C. Oligomycin
• D. Ouabain

Answer 1

The Correct Option is A

Cyanide is a known inhibitor of cytochrome complex IV in the electron transport chain (ETC). This complex, also known as cytochrome c oxidase, is crucial for the transfer of electrons from cytochrome c to oxygen. Cyanide binds to the heme group of cytochrome c oxidase, inhibiting its function and preventing electron transfer to oxygen. This blockage stops ATP synthesis, as the proton gradient necessary for ATP production via ATP synthase is no longer maintained.

Substance	Effect on ETC
Cyanide	Inhibits cytochrome complex IV
Carbon dioxide	No direct effect on ETC inhibition
Oligomycin	Inhibits ATP synthase
Ouabain	Inhibits Na⁺/K⁺ ATPase, not part of ETC