What is true about DNA polymerase used in PCR

Options

A. It is used to ligate introduced DNA in recipient cells
B. It serves as selectable marker
C. It is isolated from a virus
D. It is active at high temperature

Answer

### Step-by-Step Solution:

1. **Understanding DNA Polymerase in PCR**:
- DNA polymerase is an essential enzyme used in the Polymerase Chain Reaction (PCR) technique, which amplifies DNA.

2. **Identifying the Type of DNA Polymerase Used**:
- The specific DNA polymerase commonly used in PCR is known as Taq polymerase.

3. **Source of Taq Polymerase**:
- Taq polymerase is derived from a thermophilic bacterium called *Thermus aquaticus*. This bacterium thrives in high-temperature environments.

4. **Thermostability of Taq Polymerase**:
- One of the key features of Taq polymerase is its thermostability, meaning it remains active and functional at elevated temperatures, which is crucial for the denaturation step in PCR.

5. **Evaluating the Given Options**:
- Option 1: "It is used to ligate introduced DNA in recipient cells." - This is incorrect because ligation is performed by DNA ligase, not DNA polymerase.
- Option 2: "It serves as a selectable marker." - This is also incorrect; selectable markers are different entities used in genetic engineering.
- Option 3: "It is isolated from a virus." - This is incorrect; Taq polymerase is isolated from a bacterium, not a virus.
- Option 4: "It is active at high temperature." - This is correct, as Taq polymerase is indeed active at high temperatures.

6. **Conclusion**:
- The correct statement about DNA polymerase used in PCR is that it is active at high temperatures.

### Final Answer:
The correct option is that the DNA polymerase used in PCR is active at high temperatures.

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