(i) Name the enzyme that catalyses the transcription of hnRNA
(ii) Why does the hnRNA need to undergo changes? List the change that hnRNA undergoes and where in the cell such changes take place.
(i) RNA polymerase II.
(ii) hnRNA has non-coding sequences i.e. introns in between the coding sequences or expressed sequences i.e exons. To remove introns, it undergoes changes. that hnRNA undergoes include.
1. Capping i.e. methyl guanosine triphosphate is added to 5' end.
2. Tailing in which poly A tail of adenylate residues (200-300) are added at 3' end.
3. Splicing by which introns are removed and exons are joined with the help of ligase enzyme.