22. Match the chemical agents that interfere in oxidative phosphorylation process with their respective mode of action.

Column I           Column II
(A) Antimycin A      (i) Inhibits Fo component
of ATP synthase
(B) Oligomycine     (ii) Disrupts inner
mitochondrial
membrane potential
(C) Valinomycin     (iii) Prevent electron
transport from Fe/S
cluster to ubiquinone
(D) Rotenone        (iv) Blocks electron
transfer from
cytochrome b to
cytochrome C1
(v) Inhibits adenine
nucleotide translocase

Choose the correct combination from below:
(1) A-(ii), B-(iv), C-(v), D-(iii)
(2) A-(iv), B-(i), C-(ii), D-(iii)
(3) A-(i), B-(ii), C-(i), D-(ii)
(4) A-(v), B-(ii), C-(i), D-(ii)

Oxidative phosphorylation is a vital process in mitochondria where ATP is synthesized using energy derived from electron transport. Various chemical agents inhibit this process by targeting specific complexes or components, disrupting ATP production. Correctly matching these inhibitors to their modes of action helps in understanding mitochondrial bioenergetics and pharmacology.

Chemical Agents and Their Modes of Action

Matching Column I and Column II

Explanation

• Antimycin A acts specifically on Complex III by blocking electron flow between cytochrome b and cytochrome c1, halting the chain.

• Oligomycin binds to the Fo subunit of ATP synthase, preventing proton translocation and thus ATP synthesis.

• Valinomycin is a potassium ionophore that disrupts the electrochemical gradient by increasing membrane permeability to K⁺ ions, collapsing membrane potential.

• Rotenone inhibits Complex I by preventing electron transfer from iron-sulfur clusters to ubiquinone, stopping electron flow early in the chain.

Correct Option:

(2) A-(iv), B-(i), C-(ii), D-(iii)