Control of gene expression takes place at the level of

Options

A. DNA-replication
B. transcription
C. translation
D. None of the above

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the level at which gene expression is controlled. This involves knowing the different stages of gene expression and where regulation occurs.

2. **Identifying the Options**: The options provided are:
- DNA replication
- Transcription
- Translation
- None of the above

3. **Exploring Gene Expression Levels**: Gene expression can be controlled at various levels:
- **Transcription**: This is the first step where DNA is transcribed to mRNA. Regulation at this stage can determine whether a gene is expressed or not.
- **Translation**: This is the process where mRNA is translated into proteins. Regulation can also occur here, affecting how much protein is produced.
- **DNA Replication**: This process is primarily concerned with copying DNA and is not directly involved in the regulation of gene expression.

4. **Focusing on Prokaryotes**: The question specifically mentions prokaryotes. In prokaryotes, the primary control of gene expression occurs at the transcription level. This is because prokaryotes do not have a nucleus, and transcription and translation occur simultaneously.

5. **Conclusion**: Given the focus on prokaryotes and the understanding that transcription is the main level of control for gene expression in these organisms, the correct answer is **Transcription**.

**Final Answer**: The control of gene expression takes place at the level of **Transcription**.

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