Explain mRNA processing by Spliceosome.
Answers
Splicing is catalyzed by the spliceosome, a large RNA-protein complex composed of five small nuclear ribonucleoproteins (snRNPs, pronounced 'snurps'). Assembly and activity of the spliceosome occurs during transcription of the pre-mRNA.
The precursor of mRNA transcribed by RNA polymerase-|| it is called heterogeneous nuclear RNA .It undergoes following processing to form nascent mRNA :-
1)Splicing:- In this process the non-coding introns are removed and coding sequences call exons are joined in a definite order .This is required because primary transcript contains both introns and exons .
2)Capping:- In this process an unusual nucleotide is added to the 5' end of hnRNA.
3)Tailing:- In this process 200 to 300 adenylated residues are added at the 3' endof hn RNA .
4)The fully process mRNA is released from the nucleus into the cytoplasm for translation .
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