Assertion :During eukaryotic transcription ,in capping an unusual nucleotide (methyl guanosine triphosphate) is added to the 5'-end of hnRNA.
Reason : In tailing, adenylate residues (200-300) are added at 3'-end in a template .
Answer & explanation
Correct answer: option 3
The correct answer is Option (3)- A and R both are true but R is not the correct explanation of A .
During eukaryotic transcription , the primary transcripts contain both the exons and the introns and are non-functional. Hence, it is subjected to a process called splicing where the introns are removed and exons are joined in a defined order. hnRNA undergoes additional processing called as capping and tailing.
In capping an unusual nucleotide (methyl guanosine triphosphate) is added to the 5'-end of hnRNA.
In tailing, adenylate residues (200-300) are added at 3'-end in a template independent manner. It is the fully processed hnRNA, now called mRNA, that is transported out of the nucleus for translation.