In mitochondria, protons accumulate in the

Options

A. Outer membrane
B. Inner membrane
C. intermembrane space
D. Matrix

Answer

**Step-by-Step Solution:**

1. **Understanding Mitochondrial Structure**: Mitochondria have two membranes – an inner membrane and an outer membrane. The space between these two membranes is known as the intermembrane space, while the space inside the inner membrane is called the mitochondrial matrix.

2. **Electron Transport Chain (ETC)**: The process of respiration in mitochondria involves the Electron Transport Chain (ETC). This is a series of protein complexes located in the inner membrane of the mitochondria that facilitate the transfer of electrons from electron carriers like NADH.

3. **Proton Pumping Mechanism**: As electrons move through the ETC, energy is released. This energy is used to pump protons (H⁺ ions) from the mitochondrial matrix into the intermembrane space.

4. **Proton Accumulation**: The pumping of protons creates a higher concentration of protons in the intermembrane space compared to the matrix. This results in a proton gradient across the inner mitochondrial membrane.

5. **Conclusion**: Therefore, in mitochondria, protons accumulate in the intermembrane space due to the action of the Electron Transport Chain.

**Final Answer**: In mitochondria, protons accumulate in the intermembrane space.

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