The terminator is located

Options

A. towards 3' - end (downstream) of the coding strand
B. towards 5' - end (downstream) of the coding strand
C. toward 5' - end (upstream) of the coding strand
D. towards 3' - end (upstream) of the coding strand

Answer

**Step-by-Step Solution:**

1. **Understanding the Terminator**: The terminator is a sequence in the DNA that signals the end of transcription. It is crucial for the proper termination of RNA synthesis.

2. **Identifying the Structure of a Gene**: A typical gene structure includes:
- **Promoter**: The region where RNA polymerase binds to initiate transcription.
- **Coding Strand**: The non-template strand that has the same sequence as the mRNA (except for thymine being replaced by uracil).
- **Template Strand**: The strand that RNA polymerase uses to synthesize mRNA.

3. **Direction of Transcription**: Transcription occurs in a 5' to 3' direction. The promoter is located upstream (5' end) of the coding region, while the terminator is located downstream (3' end).

4. **Locating the Terminator**: The terminator is found at the end of the transcription unit:
- It is located at the **3' end of the coding strand**.
- It is also at the **5' end of the template strand**.

5. **Conclusion**: Therefore, the correct answer to the question "Where is the terminator located?" is that it is located at the **3' end of the coding strand**.