The source of Taq polymerase used in PCR is a :

Options

A. thermophilic fungus
B. mesophilic fungus
C. thermophilic bacterium
D. halophilic bacterium

Answer

**Step-by-Step Solution:**

1. **Understanding PCR**: PCR (Polymerase Chain Reaction) is a technique used to amplify DNA samples. It requires a special enzyme called polymerase to synthesize new DNA strands.

2. **Identifying Taq Polymerase**: Taq polymerase is the specific enzyme used in PCR. It is known for its ability to withstand high temperatures, which is crucial during the denaturation step of PCR.

3. **Temperature Tolerance**: Since PCR involves cycles of heating and cooling, the polymerase enzyme must be stable and functional at high temperatures. This is why Taq polymerase, which is derived from a thermophilic organism, is used.

4. **Exploring Options**:
- **Thermophilic Fungus**: While thermophilic fungi can survive at high temperatures, Taq polymerase is not sourced from fungi.
- **Mesophilic Fungus**: Mesophilic fungi thrive at moderate temperatures (20-45°C) and are not suitable for high-temperature PCR processes.
- **Halophilic Bacterium**: Halophilic bacteria thrive in high-salinity environments, which is not relevant for PCR.
- **Thermophilic Bacterium**: Taq polymerase is derived from the thermophilic bacterium *Thermus aquaticus*, which can survive and function at high temperatures.

5. **Conclusion**: Based on the above analysis, the correct answer is that the source of Taq polymerase used in PCR is a thermophilic bacterium.

**Final Answer**: The source of Taq polymerase used in PCR is a thermophilic bacterium.

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