Answer:tailing at 3' end protects mRNA from attack by 3' exonuclease and 5' capping is useful for recognition of mRNA
Explanation:
The mRNA formed and released from the DNA template is known as primary transcript. In mammalian system, it undergoes intensive modification to become the mature mRNA.
Post transcription processing includes removal of Introns, splicing of exons, poly-A tailing at 3'end and capping at 5' end.
The Poly-A tailing at 3' end occurs in the nucleoplasm, the 3' end is polyadenlated involves with 20-250 nucleotides long. This tail protects mRNA from attack by 3' exonuclease activity
5' end capping end also is done in the nucleus. The cap is useful in recognition of mRNA by the translating machinery.
