The unique enzyme used in PCR is

Options

A. Taq polymerase
B. gyrase
C. transcriptase
D. hexokinase

Answer

**Step-by-Step Solution:**

1. **Understanding PCR**: PCR stands for Polymerase Chain Reaction. It is a technique used to amplify (make multiple copies of) a specific segment of DNA.

2. **Identifying the Enzyme**: The key to PCR is the enzyme that facilitates the synthesis of new DNA strands. In natural DNA replication, the enzyme responsible for synthesizing new DNA strands is DNA polymerase.

3. **Unique Enzyme in PCR**: In PCR, a special type of DNA polymerase is used, which is heat-stable. This is crucial because PCR involves repeated cycles of heating and cooling. The specific enzyme used in PCR is called **Taq polymerase**. Taq polymerase is derived from the bacterium Thermus aquaticus, which thrives in high-temperature environments.

4. **Exclusion of Other Enzymes**:
- **Gyrase**: This enzyme is involved in unwinding DNA supercoils but is not used in PCR.
- **Transcriptase**: This enzyme is involved in the transcription process (RNA synthesis) and is not relevant to DNA replication in PCR.
- **Hexokinase**: This enzyme is involved in phosphorylating glucose and is not related to DNA synthesis.

5. **Conclusion**: The unique enzyme used in PCR is **Taq polymerase**.

**Final Answer**: The unique enzyme used in PCR is Taq polymerase.

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