(i) In splicing the introns are removed
and exons are joined in a defined order.
additional processing called as capping and tailing.
(ii) In capping an
unusual nucleotide (methyl guanosine triphosphate) is added to
the 5'-end of hnRNA.
(iii) In tailing, adenylate residues (200-300) are
added at 3'-end in a template independent manner.