Which of the following are the post-transcriptional events in an eukaryotic cell?A. Transport of pre-mRNA to cytoplasm prior tosplicing.B. Removal of introns and joining of exons.C. Addition of methyl group at 5’ end of hnRNA.D. Addition of adenine residues at 3’ end ofhnRNA.E. Base pairing of two complementary RNAs.Choose the correct answer from the options givenbelow
Answer
🧬 Post-Transcriptional Events in Eukaryotic Cells
🔬 Overview
In eukaryotic cells, the primary transcript (hnRNA) must undergo specific modifications to become a mature mRNA. These changes, called post-transcriptional modifications, are essential for the mRNA’s stability, transport, and translational efficiency.
✅ Key Modifications
- Splicing: Removal of introns and joining of exons by spliceosomes.
- 5′ Capping: Addition of 7-methylguanosine cap at the 5′ end for protection and ribosome binding.
- 3′ Polyadenylation (Poly-A Tailing): Addition of adenine nucleotides at the 3′ end for stability and export.
❌ Incorrect Statements Explained
- Transport to Cytoplasm: Happens after post-transcriptional processing and is not considered a modification.
- RNA Base Pairing: Involves RNA interference or duplex formation, not typical for mRNA maturation.
📊 Summary Table
| Step | Name | Description |
|---|---|---|
| 1 | Splicing | Removal of introns; joining of exons |
| 2 | 5′ Capping | Addition of 7-methylguanosine cap |
| 3 | 3′ Polyadenylation | Addition of poly-A tail |
| Not Included | Transport | Occurs after post-transcriptional processing |
| Not Applicable | RNA Base Pairing | Not a typical mRNA modification event |