With reference to processing of hn RNA, which of the following statem…

The correct answer is Option (2) → C only

In eukaryotes the first transcript, hnRNA, contains exons and introns. It is processed into functional mRNA by splicing, capping and tailing.

A. Introns are removed and exons are joined directly splicing. — A correct statement. In splicing the introns are cut out and the exons are joined in a defined order.

B. Capping & Tailing occurs at 5′ end & 3′ end respectively. — A correct statement. The cap is added at the 5′ end and the tail at the 3′ end.

C. Addition of 200-300 adenylated residues means capping. — An incorrect statement. Adding 200–300 adenylate residues at the 3′ end is tailing, not capping.

D. Addition of guanosine triphosphate takes place at 5′ end. — A correct statement. In capping an unusual nucleotide, methyl guanosine triphosphate, is added at the 5′ end.

E. Processing take place in the nucleus and converts hn RNA into functional RNA. — A correct statement. The fully processed hnRNA, now mRNA, is then sent out of the nucleus for translation.

NCERT Extract:
Types of RNA and the Process of Transcription – “… (ii) The second complexity is that 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 (Figure 5.11).”

Figure 5.11 Process of Transcription in Eukaryotes