Match the Column1 with Column 2 :
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1-d,2-b,3-a,4-c . 1-b,2-a,3-d,4-c . 1-b,2-d,3-c,4-a . 1-b,2-d,3-a,4-c . |
1-b,2-d,3-a,4-c . |
The correct answer is Option (4) -1-b,2-d,3-a,4-c.
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. |