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

Options

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

Answer

To determine which statement is true regarding DNA polymerase used in PCR, we can follow these steps:

### Step 1: Understand the Role of DNA Polymerase
DNA polymerases are enzymes that play a crucial role in DNA replication. They synthesize new strands of DNA by adding nucleotides to a growing DNA chain.

**Hint:** Recall that DNA polymerases are essential for copying DNA during replication.

### Step 2: Know What PCR Is
PCR, or polymerase chain reaction, is a technique used to amplify specific segments of DNA, producing millions of copies from a small sample.

**Hint:** Think about why amplifying DNA is important in molecular biology.

### Step 3: Identify the Type of DNA Polymerase Used in PCR
In PCR, a specific type of DNA polymerase known as Taq polymerase is used. Taq polymerase is derived from a thermophilic bacterium, which means it can withstand high temperatures.

**Hint:** Consider the conditions under which PCR operates, particularly the high temperatures involved.

### Step 4: Evaluate the Options
Now, let's analyze the provided options:

1. **It is used to ligate introduced DNA in recipient cells.** - This is incorrect; ligation is done by ligases, not polymerases.

2. **It remains active at high temperature.** - This is correct; Taq polymerase is heat-stable and remains active at the high temperatures used in PCR.

3. **It serves as a selectable marker.** - This is incorrect; DNA polymerase does not function as a selectable marker.

4. **It is isolated from a virus.** - This is incorrect; Taq polymerase is isolated from a thermophilic bacterium, not a virus.

### Step 5: Conclusion
The true statement regarding DNA polymerase used in PCR is that it remains active at high temperature.

**Final Answer:** The correct option is: **It remains active at high temperature.**