After transcription , which of the following is added to the 3' end of the eukaryotic mRNA ?

Options

A. Introns
B. Cap of modified Guanine nucleotide
C. Poly A tail
D. Trinucleotide CCA

Answer

To answer the question regarding what is added to the 3' end of eukaryotic mRNA after transcription, we can break down the process step by step:

### Step 1: Understanding Transcription
Transcription is the process where the DNA sequence of a gene is copied into messenger RNA (mRNA). This process occurs in the nucleus of eukaryotic cells.

### Step 2: Post-Transcriptional Modifications
After transcription, eukaryotic mRNA undergoes several modifications before it can be translated into a protein. These modifications include:
- Splicing
- Capping
- Tailing

### Step 3: Splicing
Splicing involves the removal of non-coding sequences called introns from the primary mRNA transcript. The remaining coding sequences, called exons, are then joined together to form a continuous coding sequence.

### Step 4: Capping
Capping refers to the addition of a 7-methylguanylate (7-mG) cap to the 5' end of the mRNA. This cap is important for mRNA stability and is involved in the initiation of translation.

### Step 5: Tailing
The final modification is the addition of a poly-A tail. This involves the cleavage of the 3' end of the mRNA transcript and the addition of a stretch of adenine (A) nucleotides, typically 200-250 A residues. This poly-A tail enhances the stability of the mRNA and aids in its export from the nucleus.

### Conclusion
Thus, the correct answer to the question is that a **poly-A tail** is added to the 3' end of the eukaryotic mRNA after transcription.

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