In a DNA segment, all of the following are region of transcription unit except :

Options

A. Promoter
B. Structural gene
C. Terminator
D. Elongator

Answer

To determine which of the provided options is not a region of a transcription unit in a DNA segment, we can analyze the components of a transcription unit. A transcription unit typically consists of the following regions:

1. **Promoter Region**: This is the sequence where RNA polymerase binds to initiate transcription. It is crucial for the start of the transcription process.

2. **RNA Coding Sequence**: This is the region that is transcribed into RNA. It contains the information for the synthesis of proteins and includes the coding sequences for structural genes.

3. **Terminator Sequence**: This sequence signals the end of transcription. It is essential for terminating the transcription process and releasing the newly formed RNA molecule.

Now, let’s analyze the options provided in the question:

- **Promoter**: This is a region of the transcription unit.
- **RNA Coding Sequence**: This is also a region of the transcription unit.
- **Terminator Sequence**: This is another region of the transcription unit.
- **Elongation**: This is not a region; rather, it is an event that occurs during transcription when the RNA strand is being synthesized.

Based on this analysis, the correct answer is that "Elongation" is not a region of the transcription unit.

**Final Answer**: Elongation