In eukaryotes, the first level of regulation of gene expressionis

Options

A. Transcription
B. Translation
C. Transport of mRNA from nucleus to the cytoplasm
D. Regulation of splicing

Answer

To solve the question regarding the first level of regulation of gene expression in eukaryotes, we can break down the process step by step:

### Step-by-Step Solution:

1. **Understanding Gene Expression**:
- Gene expression in eukaryotes involves multiple steps, starting from DNA and leading to the production of proteins. The main stages include replication, transcription, translation, and post-translational modifications.

2. **Identifying the Steps**:
- The first step after DNA replication is **transcription**, where DNA is converted into RNA.
- This process involves the synthesis of a primary RNA transcript (heteronuclear RNA), which is then processed into mature mRNA.

3. **Regulation of Transcription**:
- Transcription is regulated by various elements such as promoters, enhancers, and silencers. These regulatory sequences control the binding of RNA polymerase and other transcription factors, determining whether a gene is expressed or not.

4. **Post-Transcriptional Modifications**:
- After transcription, the primary RNA undergoes modifications such as splicing, capping, and polyadenylation before it becomes mature mRNA. While these processes also involve regulation, they occur after the transcription step.

5. **Translation and Further Regulation**:
- The next step is translation, where mRNA is translated into proteins. Although this step is also regulated, it is not the first level of regulation.

6. **Conclusion**:
- Since transcription is the first step where regulation of gene expression occurs, the answer to the question is **transcription**.

### Final Answer:
The first level of regulation of gene expression in eukaryotes is **transcription**.

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