what is meant by capping and tailing in transcription process in eukaryotes?
The precursor of mRNA is called heterogeneous nuclear RNA (hnRNA). hnRNA undergoes two additional processing called capping and tailing. In capping an unusual nucleotide (methyl guanosine triphosphate) is added to the 5'-end of hnRNA and helps in recognition of mRNA by the ribosome and its protection from RNases. In tailing, adenine nucleotides are added at 3'-end or tail of hnRNA which is important in maintaining the stability of RNA, export from the nucleus and translation.