What happens in tailing process of transcriptions?

Options

A. Adenylate residue added at 5' end of RNA
B. Adenylate residue added at 3' end of RNA
C. Guanylate residue added at 5' end of RNA
D. Guanylate residue added at 3' end of RNA

Answer

### Step-by-Step Solution:

1. **Understanding Transcription:**
- Transcription is the process by which messenger RNA (mRNA) is synthesized from a DNA template. This occurs in the nucleus of the cell.

2. **Post-Transcriptional Modifications:**
- After the mRNA is synthesized, it undergoes several modifications before it can be transported to the cytoplasm for protein synthesis. These modifications are essential for the stability and functionality of the mRNA.

3. **5' Cap Addition:**
- A 5' cap, specifically a 7-methylguanosine cap, is added to the 5' end of the mRNA. This cap protects the mRNA from degradation and assists in ribosome binding during translation.

4. **Tailing Process (Polyadenylation):**
- The tailing process refers to the addition of a polyadenyl tail (poly-A tail) to the 3' end of the mRNA. This tail consists of a long chain of adenine nucleotides (adenylate residues).
- The addition of the poly-A tail enhances the stability of the mRNA and facilitates its export from the nucleus to the cytoplasm.

5. **Importance of Tailing:**
- The poly-A tail prevents the degradation of mRNA during its transport and ensures that the mRNA remains intact for translation into protein.

6. **Correct Answer Identification:**
- Among the options provided:
- The correct statement regarding the tailing process is that adenylate residues are added at the 3' end of RNA.