Gujarat BoardEnglish MediumSTD 12 ScienceBIOLOGYMolecular Basis of Inheritance3 Marks
Question
Explain the post-transcriptional modifications, the hnRNA undergoes in eukaryotic cells.
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Answer
Since eukaryotes have split gene arrangement, the hRNA has both coding sequences (exons) and non-coding sequences (introns) and is non-functional; so it has to undergo splicing, the process, in which introns are removed and exons are joined.
It has to undergo two other processes, namely capping and tailing to become functional.
In capping, an unusual nucleotide, called methyl guanosine triposphate residues are added at the 5' end of hnRNA.
In-tailing, about 200-300 adenylate residues are added at the 3' end, in a template-independent manner.
These changes take place in the nucleus of the cell.
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