Question

2,4-Dinitrophenol (DNP) is an uncoupler that

• A. cannot freely pass through plasma membrane
• B. enhances ATP production
• C. is a non-toxic compound at high dose
• D. makes the inner mitochondrial membrane leaky to protons

Hint:

Uncouplers like DNP increase heat production in cells by dissipating the proton gradient, reducing ATP synthesis efficiency.

Answer 1

The Correct Option is D

Step 1: Understanding DNP’s Mechanism.
DNP acts as an uncoupler by allowing protons to pass through the mitochondrial membrane, bypassing ATP synthase. This disrupts the proton gradient and reduces ATP production, but still allows the electron transport chain to function.
Step 2: Analyzing the Options.
- (A) Incorrect. DNP can pass through the plasma membrane due to its lipophilic nature.
- (B) Incorrect. DNP inhibits ATP production by uncoupling oxidative phosphorylation.
- (C) Incorrect. DNP is toxic, especially at high doses, as it causes excessive heat production and energy inefficiency.
- (D) Correct. DNP makes the mitochondrial membrane leaky to protons, reducing the proton gradient.
Step 3: Conclusion.
Thus, the correct answer is (D).