The correct sequence of different steps of polymerease chain reaction is
1) annealing → denaturation → extension
2) denaturation → extension → annealing
3) denaturation → annealing → extension
4) extension → denaturation → annealing

Options

A. 1) annealing `rarr` denaturation `rarr` extension
B. 2) denaturation `rarr` extension `rarr` annealing
C. 3) denaturation `rarr` annealing `rarr` extension
D. 4) extension `rarr` denaturation `rarr` annealing

Explanation

To solve the question regarding the correct sequence of steps in the Polymerase Chain Reaction (PCR), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Steps of PCR**:
The three main steps in the PCR process are:
- **Denaturation**: The double-stranded DNA is heated to separate it into two single strands.
- **Annealing**: Primers bind to the single-stranded DNA at specific locations.
- **Extension**: DNA polymerase synthesizes new DNA strands by adding nucleotides to the primers.

2. **Determine the Correct Sequence**:
- The first step is **Denaturation** where the DNA strands are separated.
- The second step is **Annealing** where the primers attach to the single-stranded DNA.
- The third step is **Extension** where the new DNA strands are synthesized.

3. **Match with Given Options**:
- **Option 1**: Annealing → Denaturation → Extension (Incorrect)
- **Option 2**: Denaturation → Extension → Annealing (Incorrect)
- **Option 3**: Denaturation → Annealing → Extension (Correct)
- **Option 4**: Extension → Denaturation → Annealing (Incorrect)

4. **Conclusion**:
The correct sequence of steps in PCR is **Denaturation → Annealing → Extension**, which corresponds to **Option 3**.

### Final Answer:
The correct sequence of different steps of polymerase chain reaction is **Option 3: Denaturation → Annealing → Extension**.