Question

Which of the following are the post-transcriptional events in an eukaryotic cell? (A) Transport of pre-mRNA to cytoplasm prior to splicing.
(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 of hnRNA.
(E) Base pairing of two complementary RNAs.
Choose the correct answer from the options given below:

• A. B, C, D only
• B. B, C, E only
• C. C, D, E only
• D. A, B, C only

Hint:

Post-transcriptional modifications in eukaryotic cells include RNA splicing, capping, and polyadenylation, all of which prepare mRNA for translation.

Answer 1

The Correct Option is A

Analysis of each statement:

(A) "Transport of pre-mRNA to cytoplasm prior to splicing" is inaccurate. Splicing and other modifications (e.g., capping, polyadenylation) occur in the nucleus before mRNA transport to the cytoplasm.
(B) "Removal of introns and joining of exons" is accurate. This is RNA splicing, a crucial post-transcriptional event that takes place in the nucleus.
(C) "Addition of methyl group at 5' end of hnRNA" is accurate. This process, known as 5' capping, protects the mRNA and aids ribosome recognition.
(D) "Addition of adenine residues at 3' end of hnRNA" is accurate. This is polyadenylation, which adds a poly-A tail to the mRNA, enhancing stability and transport.
(E) "Base pairing of two complementary RNAs" is inaccurate. This is not a post-transcriptional event but can occur during translation or RNA interference.

Therefore, the correct statements are B, C, and D.