(a) Describe the process of synthesis of fully functional mRNA in a eukaryotic cell.
(b) How is this process of mRNA synthesis different from that in prokaryotes?
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(a) Describe the process of synthesis of fully functional mRNA in a eukaryotic cell. <br> (b) How is this process of mRNA synthesis different from that in prokaryotes?
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A)
(a) Synthesis of mRNA in eukaryotes.
* RNA polymerase II transcribes the precursor of mRNA, called heterogeneous nuclear RNA (hnRNA).
* This primary transcript contains both coding sequences (exons) and non- coding sequences (introns) and is non-functional. So it has to undergo splicing, i.e.removal of introns and joining of exons.
* After splicing, the hnRNA has to undergo capping, i.e. the process in which an unusual nucleotide, methyl guanosine triphosphate is added 5' end.
* Then it undergoes tailing, the process in which about 200-300 adenylate residues are added at the 3' end of hnRNA.
* This fully processed hnRNA is now called mRNA and is ready for release into cytoplasm for translation.
b) In prokaryotes structure genes are polycistronic and continues and thus it does not need splicing to form mRNA. Whereas in eukaryotes hnRNA is formed which contains coding and non coding region and needs to remove non coding region by splicing to form mature mRNA.......
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