The promoter site and the terminator site for transcription are located at:

Options

A. 3' (downstream) end and 5' (upstream) end, respectively of the transcription unit
B. 5' (upstream) end and 3' (downstream) end, respectively of the transcription unit
C. The 5' (upstream) end
D. The 3' (downstream) end

Answer

**Step-by-Step Solution:**

1. **Understanding Transcription**: Transcription is the process through which RNA is synthesized from a DNA template. This involves the conversion of the genetic information from DNA into RNA.

2. **Identifying the Promoter Region**: The promoter is a specific region on the DNA where RNA polymerase binds to initiate transcription. This region is crucial for the transcription process as it signals the start of RNA synthesis.

3. **Location of the Promoter**: The promoter is located in the upstream region of the gene, which means it is found before the start site of transcription on the DNA strand. Specifically, it is situated at the 5' end of the DNA strand.

4. **Identifying the Terminator Region**: The terminator is a sequence of nucleotides that signals the end of transcription. It tells RNA polymerase to stop synthesizing RNA.

5. **Location of the Terminator**: The terminator is located in the downstream region of the gene, which means it is found after the coding sequence of the gene. Specifically, it is situated at the 3' end of the DNA strand.

6. **Conclusion**: Therefore, the promoter site is located at the 5' upstream end of the DNA, and the terminator site is located at the 3' downstream end of the DNA.

**Final Answer**: The promoter site is at the 5' upstream end, and the terminator site is at the 3' downstream end.

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