Uncoupler of oxidative phosphorylation –
**Core Concept**
The question tests understanding of **oxidative phosphorylation** and its regulation. Oxidative phosphorylation is a process in which **ATP** is formed as a result of the transfer of electrons from **NADH** or **FADH2** to **oxygen** in the **mitochondrial inner membrane**. Uncouplers are agents that disrupt this process.
**Why the Correct Answer is Right**
An uncoupler increases the permeability of the **mitochondrial inner membrane**, allowing **protons** to flow back into the **mitochondrial matrix** without passing through **ATP synthase**, thus preventing the generation of **ATP**. This process is crucial for maintaining the **proton gradient** necessary for **ATP production**.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it is not specified.
**Option B:** Incorrect because it is not specified.
**Option C:** Incorrect because it is not specified.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that **2,4-dinitrophenol** is a classic example of an uncoupler of oxidative phosphorylation. It can be used to illustrate the concept of uncoupling in **mitochondrial function**.
**Correct Answer:** D. 2,4-dinitrophenol.