Carbonic anhydrase enzyme exists

Options

A. mainly in plasma
B. only in plasma
C. mainly in RBC
D. only in RBC

Answer

To solve the question regarding the existence of the carbonic anhydrase enzyme, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Function of Carbonic Anhydrase**:
- Carbonic anhydrase is an enzyme that catalyzes the conversion of carbon dioxide (CO2) and water (H2O) into carbonic acid (H2CO3), which then dissociates into bicarbonate ions (HCO3-) and hydrogen ions (H+).

2. **Location of Carbonic Anhydrase**:
- This enzyme is primarily found in red blood cells (RBCs). It plays a crucial role in the transport of carbon dioxide in the blood.

3. **Role in CO2 Transport**:
- In the bloodstream, about 20-25% of carbon dioxide is transported by red blood cells, while approximately 70% is transported as bicarbonate ions. The presence of carbonic anhydrase in RBCs facilitates this conversion.

4. **Reversible Reaction**:
- The reaction catalyzed by carbonic anhydrase is reversible. In the lungs, the bicarbonate ions can be converted back to carbon dioxide and water, allowing CO2 to be exhaled.

5. **Conclusion**:
- Based on the information gathered, carbonic anhydrase is mainly present in red blood cells (RBCs). Therefore, the correct answer to the question is option C: mainly in RBC.

### Final Answer:
C. Mainly in RBC

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