Identify the membrane across which the proton ` (H^(+))` gradient facilitates ATP synthesis in a typical eukaryotic cell

Options

A. Plasma membrane
B. Mitochondrial outer membrane
C. Mitochondrial inner membrane
D. Nulear membrane.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the specific membrane in a eukaryotic cell where the proton (H⁺) gradient is utilized to synthesize ATP.

2. **Identifying the Process**: The synthesis of ATP using a proton gradient is primarily associated with the process of oxidative phosphorylation, which occurs during aerobic respiration.

3. **Locating the Site of ATP Synthesis**: In eukaryotic cells, the electron transport chain (ETC) is located in the mitochondria. The ETC is responsible for creating the proton gradient.

4. **Identifying the Relevant Membrane**: The electron transport chain occurs across the mitochondrial inner membrane. This membrane is crucial because it separates the mitochondrial matrix from the intermembrane space.

5. **Understanding the Proton Gradient**: As electrons are transferred through the proteins of the electron transport chain, protons (H⁺ ions) are pumped from the mitochondrial matrix into the intermembrane space, creating a proton gradient.

6. **ATP Synthesis Mechanism**: The proton gradient generated across the mitochondrial inner membrane drives ATP synthesis through ATP synthase, which utilizes the flow of protons back into the matrix to convert ADP and inorganic phosphate into ATP.

7. **Conclusion**: Therefore, the membrane across which the proton (H⁺) gradient facilitates ATP synthesis in a typical eukaryotic cell is the **mitochondrial inner membrane**.

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