Match the Column1 with Column 2 :
| Column 1 | Column 2 |
| 1) RNA polymerase I | a) Transcription of tRNA, 5srRNA, and snRNAs |
| 2) RNA polymerase II | b) Transcribes rRNAs |
| 3) RNA polymerase III | c) Addition of adenylate residues at 3'-end |
| 4) Tailing | d) Transcribes precursor of mRNA (hnRNA) |
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) -1-b,2-d,3-a,4-c.
| Column 1 | Column 2 |
| 1) RNA polymerase I | b) Transcribes rRNAs |
| 2) RNA polymerase II | d) Transcribes precursor of mRNA (hnRNA) |
| 3) RNA polymerase III | a) Transcription of tRNA, 5srRNA, and snRNAs |
| 4) Tailing | c) Addition of adenylate residues at 3'-end |
In eukaryotes, there are at least three RNA polymerases in the nucleus (in addition to the RNA polymerase found in the organelles). There is a clear cut division of labour.
(i) The RNA polymerase I transcribes rRNAs (28S, 18S, and 5.8S).
(ii) RNA polymerase III is responsible for transcription of tRNA, 5srRNA, and snRNAs (small nuclear RNAs).
(iii) The RNA polymerase II transcribes precursor of mRNA, the heterogeneous nuclear RNA (hnRNA).
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 tailing, adenylate residues (200-300) are added at 3'-end in a template independent manner.