Poly A tail is present in

Options

A. mRNA of bacteria
B. tRNA of eukaryotes
C. Promoter of bacteria
D. mRNA of eukaryotes

Answer

To solve the question "Poly A tail is present in," we will analyze the options provided and determine where the Poly A tail is found.

### Step-by-Step Solution:

1. **Understanding Poly A Tail**: The Poly A tail is a stretch of adenine nucleotides added to the 3' end of a messenger RNA (mRNA) molecule. This modification occurs after the transcription of the gene.

2. **Identifying the Options**: The options given are:
- Messenger RNA of bacteria
- tRNA of eukaryotes
- Promoter of bacteria
- Messenger RNA of eukaryotes

3. **Analyzing Each Option**:
- **Messenger RNA of bacteria**: Bacterial mRNA does not have a Poly A tail. Instead, bacterial mRNA is typically not processed in the same way as eukaryotic mRNA.
- **tRNA of eukaryotes**: tRNA molecules do not have a Poly A tail. They undergo different modifications and are not the focus of this question.
- **Promoter of bacteria**: Promoters are regions of DNA that initiate transcription and do not contain a Poly A tail.
- **Messenger RNA of eukaryotes**: Eukaryotic mRNA undergoes several processing steps, including the addition of a Poly A tail at the 3' end after transcription.

4. **Conclusion**: The Poly A tail is specifically added to the messenger RNA of eukaryotes during the transcription process. This addition is crucial for mRNA stability and transport from the nucleus to the cytoplasm.

### Final Answer:
The correct answer is **Messenger RNA of eukaryotes**.

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