Match List-I with List-II.
| List-I | List-II |
|---|---|
| A. RNA polymerase I | I. Transcription of tRNA, 5S rRNA and snRNAs |
| B. RNA polymerase II | II. Transcription of rRNAs (28S, 18S and 5.8S) |
| C. RNA polymerase III | III. Addition of adenylate residues at the 3'-end |
| D. Tailing | IV. Transcription of hnRNA |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → A-II, B-IV, C-I, D-III
Eukaryotes have at least three RNA polymerases in the nucleus, each with its own job. The primary transcript (hnRNA) is then processed by splicing, capping and tailing.
(A) RNA polymerase I — this matches (II) Transcription of rRNAs (28S, 18S and 5.8S). These are the large rRNAs of the ribosome.
(B) RNA polymerase II — this matches (IV) Transcription of hnRNA. hnRNA (heterogeneous nuclear RNA) is the precursor of mRNA.
(C) RNA polymerase III — this matches (I) Transcription of tRNA, 5S rRNA and snRNAs. The small 5S rRNA is made by this enzyme, not by polymerase I.
(D) Tailing — this matches (III) Addition of adenylate residues at the 3′-end. The poly A tail is added without any template.
The correct code is A-II, B-IV, C-I, D-III.
NCERT Extract:
Types of RNA and the Process of Transcription – “… There is a clear cut division of labour. The RNA polymerase I transcribes rRNAs (28S, 18S, and 5.8S), whereas the RNA polymerase III is responsible for transcription of tRNA, 5srRNA, and snRNAs (small nuclear RNAs). The RNA polymerase II transcribes precursor of mRNA, the heterogeneous nuclear RNA (hnRNA).”
Types of RNA and the Process of Transcription – “… 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.”