Find out the correct sequence of PCR

Options

A. (i) Annealing (ii) Denaturation (iii) Extension
B. (i) Denaturation (ii) Extension (iii) Annealing
C. (i) Denaturation (ii) Annealing (iii) Extension
D. (i) Extension (ii) Denaturation (iii) Annealing

Answer

To find the correct sequence of the Polymerase Chain Reaction (PCR), we need to understand the three main steps involved in the process. Here’s a step-by-step breakdown:

### Step 1: Denaturation
- **Explanation**: The first step of PCR involves heating the DNA sample to around 92-98 degrees Celsius. This high temperature causes the double-stranded DNA to separate into two single strands. This process is known as denaturation because the heat disrupts the hydrogen bonds between the base pairs, effectively "denaturing" the DNA structure.

### Step 2: Annealing
- **Explanation**: After denaturation, the temperature is lowered to around 50-65 degrees Celsius. During this step, short sequences of nucleotides known as primers bind (or anneal) to the complementary sequences on the single-stranded DNA. This is crucial because the primers provide a starting point for DNA synthesis.

### Step 3: Extension
- **Explanation**: The final step involves raising the temperature to around 72 degrees Celsius, which is the optimal temperature for the enzyme Taq polymerase. This enzyme synthesizes new DNA strands by adding nucleotides to the 3' end of the primers, effectively extending the DNA strand.

### Conclusion
Based on the above steps, the correct sequence of PCR is:
1. Denaturation
2. Annealing
3. Extension

Thus, the correct answer is **Option C: Denaturation, Annealing, Extension**.

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