Which one is a true statement regarding DNA polymerase used in PCR

Options

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

Answer

To determine the true statement regarding DNA polymerase used in PCR (Polymerase Chain Reaction), let's analyze the options provided step by step.

### Step 1: Understand the Function of DNA Polymerase in PCR
DNA polymerase is an enzyme that synthesizes new strands of DNA complementary to the template strand during the PCR process. It is essential for amplifying specific DNA sequences.

**Hint:** Recall the role of DNA polymerase in DNA replication and amplification processes.

### Step 2: Evaluate Each Statement
1. **It is isolated from a virus.**
- This statement is **false**. While some DNA polymerases can be derived from viruses, the most commonly used DNA polymerase in PCR, Taq polymerase, is derived from the bacterium Thermus aquaticus, not a virus.

2. **It is used to ligate introduced DNA in the recipient cells.**
- This statement is **false**. Ligase enzymes are responsible for joining DNA fragments together, not DNA polymerases. Therefore, this option is incorrect.

3. **It acts as a selectable marker.**
- This statement is **false**. Selectable markers are typically genes that confer resistance to antibiotics or other traits that allow for the identification of successfully transformed cells. DNA polymerase does not serve this function.

4. **It remains active at high temperature.**
- This statement is **true**. Taq polymerase, the enzyme commonly used in PCR, is heat-stable and can withstand the high temperatures used during the denaturation step of PCR, making it ideal for this process.

### Step 3: Identify the Correct Statement
Based on the evaluation, the only true statement regarding DNA polymerase used in PCR is that it remains active at high temperatures.

**Final Answer:** The true statement regarding DNA polymerase used in PCR is that it remains active at high temperature.

---