All enzymes of TCA cycle are located in the mitochondrial matrix except one which is located in inner mitochondrial membranes in eukaryotes and in cytosol in prokaryotes. This enzyme is

Options

A. isocitrate dehydrogenase
B. ketoglutarate dehydrogenase
C. succinate dehydrogenase
D. lactate dehydrogenase.

Explanation

**Step-by-Step Solution:**

1. **Understanding the TCA Cycle**: The TCA cycle, also known as the Krebs cycle or citric acid cycle, is a series of enzymatic reactions that occur in the mitochondria of eukaryotic cells. It plays a crucial role in cellular respiration by converting acetyl-CoA into carbon dioxide and transferring energy to electron carriers.

2. **Location of TCA Cycle Enzymes**: Most enzymes involved in the TCA cycle are located in the mitochondrial matrix. This is where the majority of the reactions take place.

3. **Identifying the Exception**: The question specifies that there is one enzyme that is not located in the mitochondrial matrix. Instead, it is found in the inner mitochondrial membrane in eukaryotes and in the cytosol in prokaryotes.

4. **Recognizing the Enzyme**: The enzyme that fits this description is succinate dehydrogenase. This enzyme is unique because it is associated with the inner mitochondrial membrane and plays a dual role in both the TCA cycle and the electron transport chain.

5. **Function of Succinate Dehydrogenase**: Succinate dehydrogenase catalyzes the conversion of succinate to fumarate in the TCA cycle. This reaction is significant as it also contributes to the electron transport chain by transferring electrons to ubiquinone (coenzyme Q).

6. **Conclusion**: Therefore, the enzyme that is located in the inner mitochondrial membrane in eukaryotes and in the cytosol in prokaryotes is succinate dehydrogenase.

**Final Answer**: Succinate dehydrogenase.

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