Which of the following enzymes is absent in mitochondria

Options

A. Aconitase
B. Maleic dehydrogenase
C. Hexokinase
D. None of these

Explanation

To determine which enzyme is absent in mitochondria from the given options (Aconitase, Malic Dehydrogenase, Hexokinase), we can analyze the functions and locations of each enzyme:

1. **Understanding the Enzymes**:
- **Aconitase**: This enzyme is involved in the citric acid cycle (Krebs cycle) and is located in the mitochondria. It catalyzes the conversion of citrate to isocitrate.
- **Malic Dehydrogenase**: This enzyme is also part of the citric acid cycle and is found in the mitochondria. It catalyzes the conversion of malate to oxaloacetate.
- **Hexokinase**: This enzyme plays a crucial role in glycolysis, which occurs in the cytoplasm. It catalyzes the phosphorylation of glucose to form glucose-6-phosphate.

2. **Identifying the Location**:
- Aconitase and Malic Dehydrogenase are both present in the mitochondria as they are involved in the Krebs cycle.
- Hexokinase, on the other hand, is located in the cytoplasm and is not found in mitochondria.

3. **Conclusion**:
Based on the analysis, the enzyme that is absent in mitochondria is **Hexokinase**.

### Final Answer:
**Hexokinase** is the enzyme that is absent in mitochondria.

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