Select the correct sequence of steps involved in PCR during gene amplification.
(a) Denaturation , annealing , extension
(b) Denaturation , extension , annealing
(c) Extension , Denaturation, Annealing
(d) Annealing , extension , denaturation

Options

A. Denaturation , annealing , extension
B. Denaturation , extension , annealing
C. Extension , Denaturation, Annealing
D. Annealing , extension , denaturation

Answer

To solve the question regarding the correct sequence of steps involved in PCR (Polymerase Chain Reaction) during gene amplification, we can break down the process as follows:

### Step-by-Step Solution:

1. **Understanding PCR**:
- PCR is a technique used to amplify specific segments of DNA. It involves a series of temperature changes that facilitate the replication of the DNA.

2. **Step 1 - Denaturation**:
- The first step in PCR is denaturation. This occurs at a high temperature (around 94-95°C), which causes the double-stranded DNA to separate into two single strands. This step is crucial as it provides the single-stranded templates needed for the next steps.

3. **Step 2 - Annealing**:
- After denaturation, the temperature is lowered to allow primers to bind (anneal) to the single-stranded DNA. Primers are short sequences of nucleotides that are complementary to the target DNA sequence. This step typically occurs at a temperature around 50-65°C.

4. **Step 3 - Extension**:
- The final step is extension. The temperature is raised to about 72°C, which is the optimal temperature for the enzyme Taq polymerase. This enzyme synthesizes new DNA strands by adding nucleotides to the primers, effectively extending the DNA strand.

5. **Conclusion**:
- The correct sequence of steps in PCR is: Denaturation → Annealing → Extension. Therefore, the correct answer is option (a) Denaturation, Annealing, Extension.

### Final Answer:
The correct sequence of steps involved in PCR during gene amplification is **(a) Denaturation, Annealing, Extension**.