The core enzyme requires a factor for termination of RNA synthesis at some sites. This is known as

Options

A. Sigma factor
B. Rho factor
C. Gamma factor
D. Alpha particle

Answer

To answer the question regarding the factor required for the termination of RNA synthesis at some sites by the core enzyme, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding RNA Synthesis**:
- RNA synthesis, or transcription, is the process where RNA is synthesized from a DNA template. This process involves three main stages: initiation, elongation, and termination.

2. **Role of RNA Polymerase**:
- The enzyme responsible for RNA synthesis is RNA polymerase, also known as DNA-dependent RNA polymerase. This enzyme is crucial for carrying out all three stages of transcription.

3. **Initiation Phase**:
- During the initiation phase, RNA polymerase binds to a specific region of the DNA known as the promoter. This binding is facilitated by a protein factor known as the sigma factor.

4. **Elongation Phase**:
- After initiation, the RNA polymerase moves along the DNA template, adding ribonucleotides to form the growing RNA strand. This phase is called elongation.

5. **Termination Phase**:
- The final phase of transcription is termination. At this stage, RNA polymerase must detach from the RNA molecule and the DNA template to complete the transcription process.

6. **Factor Required for Termination**:
- In prokaryotes, the termination of RNA synthesis can occur through two mechanisms: Rho-dependent and Rho-independent termination. The factor that is specifically required for Rho-dependent termination is known as the **Rho factor**.

7. **Conclusion**:
- Therefore, the answer to the question is that the core enzyme requires the Rho factor for the termination of RNA synthesis at some sites.

### Final Answer:
The factor required for termination of RNA synthesis at some sites is known as the **Rho factor**.

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