Which of the following region is not present in transcription unit in DNA :-

Options

A. Promoter
B. Structural gene
C. Terminator
D. N-terminal

Answer

To determine which region is not present in the transcription unit of DNA, let's analyze the options provided:

1. **Promoter**:
- The promoter is a specific DNA sequence where RNA polymerase binds to initiate transcription. It is essential for the transcription process and is considered part of the transcription unit.

2. **Structural Gene**:
- The structural gene is the segment of DNA that is transcribed into RNA. This RNA may then be translated into a protein. Since the structural gene is the primary component of the transcription unit, it is included.

3. **Terminator**:
- The terminator is a sequence of DNA that signals the end of transcription. It is crucial for the proper termination of RNA synthesis, making it a part of the transcription unit as well.

4. **N-terminal**:
- The N-terminal refers to the beginning end of a protein or polypeptide chain, which is formed after the transcription and translation processes. It is not a part of the transcription unit in DNA.

Based on this analysis, the region that is not present in the transcription unit of DNA is the **N-terminal**.

### Step-by-step Solution:
1. Identify the components of a transcription unit: promoter, structural gene, and terminator.
2. Analyze each option to see if it is part of the transcription unit.
3. Conclude that the N-terminal is not part of the transcription unit.

### Final Answer:
The region that is not present in the transcription unit in DNA is the **N-terminal**.