Question

Which one or more of the following statements is/are correct in the processing of pre-mRNA in eukaryotes?

• A. ( 3→ 5 exonuclease activity is involved in the conversion of pre-mRNA to mRNA. )
• B. ( 5-capping and addition of 3- poly A tail precedes splicing. )
• C. ( Splicing of pre-mRNA occurs via transesterification reaction. )
• D. ( Alternative splicing can yield different mRNA products from the same pre-mRNA. )

Hint:

Understanding the mechanisms of pre-mRNA processing is essential for grasping how genetic information is regulated and expressed in eukaryotic cells, affecting everything from cellular function to organismal development.

Answer 1

The Correct Option is C

Detailed Explanation of Each Statement: 
(A) 3→ 5 exonuclease activity: This statement is incorrect for pre-mRNA processing. 3 to 5 exonuclease activity is typically associated with DNA polymerase proofreading during DNA replication, not mRNA processing. 
(B) 5-capping and addition of 3- poly A tail precedes splicing: This statement is generally incorrect. 5 capping occurs co-transcriptionally, early in the synthesis of pre-mRNA, but the polyadenylation at the 3' end typically occurs after the splicing of pre-mRNA. 
(C) Transesterification in splicing: Correct. Splicing of pre-mRNA indeed involves transesterification reactions, where chemical bonds are rearranged by breaking and forming phosphate ester links. 
(D) Alternative splicing: Also correct. Alternative splicing allows for the generation of multiple mRNA molecules from a single pre-mRNA sequence by varying the pattern of exon inclusion and/or exclusion. Conclusion:
Statements (C) and (D) accurately describe critical aspects of pre-mRNA processing in eukaryotes, emphasizing the biochemical mechanisms and functional diversity in gene expression.