PCR proceeds in three distinct steps governed by temperature they are in order of :

Options

A. Synthesis, Annealing, Denuturation
B. Annealing, Synthesis, Denaturation
C. Denaturation, Synthesis, Annealing
D. Denaturation, Annealing, Synthesis

Answer

**Step-by-Step Solution:**

1. **Understanding PCR**: PCR, or Polymerase Chain Reaction, is a technique used in molecular biology to amplify specific DNA sequences. It allows for the creation of millions of copies of a particular DNA segment.

2. **Identifying the Steps of PCR**: PCR consists of three main steps, each governed by specific temperature conditions:
- **Denaturation**: This is the first step where the double-stranded DNA is heated to around 94-95°C, causing the strands to separate into single strands. This process is essential for exposing the DNA sequences that need to be amplified.

- **Annealing**: The second step occurs at a lower temperature, typically between 50-56°C. During this phase, short DNA primers bind (or anneal) to the single-stranded DNA templates. These primers are necessary for the synthesis of new DNA strands.

- **Synthesis (Extension)**: The third step involves the synthesis of new DNA strands. This occurs at a temperature optimal for the DNA polymerase enzyme (usually around 72°C). The enzyme extends the primers, synthesizing new strands of DNA complementary to the template strands.

3. **Ordering the Steps**: Based on the descriptions of each step:
- First: **Denaturation**
- Second: **Annealing**
- Third: **Synthesis**

4. **Conclusion**: The correct order of the steps in PCR, governed by temperature, is **Denaturation, Annealing, and Synthesis**.

**Final Answer**: The correct option is **Denaturation, Annealing, and Synthesis**.

---