Which of the following steps in transcription is catalysed by RNA polymerse?

Options

A. Initiation
B. Elongation
C. Termination
D. All of the above

Explanation

To answer the question "Which of the following steps in transcription is catalyzed by RNA polymerase?", we need to analyze the options provided:

1. **Initiation**
2. **Elongation**
3. **Termination**
4. **All of the above**

### Step-by-Step Solution:

1. **Understanding Transcription**:
Transcription is the process by which DNA is converted into RNA. This process involves several key steps: initiation, elongation, and termination.

2. **Role of RNA Polymerase**:
RNA polymerase is the enzyme responsible for synthesizing RNA from the DNA template. It catalyzes the transcription process.

3. **Analyzing Each Step**:
- **Initiation**: This is the first step where RNA polymerase binds to the promoter region of the DNA and starts synthesizing RNA. RNA polymerase catalyzes this step.
- **Elongation**: In this step, RNA polymerase continues to add nucleotides to the growing RNA strand, extending it in the 5' to 3' direction. This step is also catalyzed by RNA polymerase.
- **Termination**: This is the final step where RNA polymerase reaches a termination signal and releases the newly synthesized RNA molecule. RNA polymerase catalyzes this step as well.

4. **Conclusion**:
Since RNA polymerase catalyzes all three steps of transcription (initiation, elongation, and termination), the correct answer is **All of the above**.

### Final Answer:
**All of the above** (1, 2, and 3 are all catalyzed by RNA polymerase).

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