Question

Why in Eukaryotes primary transcript undergo maturation before becoming functional?

Answer 1

Dear Student,

hnRNA (also known as pre-mRNA) is a primary transcript formed after transcription of DNA. hnRNA contains introns (regions of RNA that do not code for proteins) and exons. It undergoes a process called splicing in which introns are excised and exons are joined together. After this, 7-methylguanosine is added at the 5' end of hnRNA and about 200-300 adenine residues are added at 3′-end in a template independent manner. This synthesises a poly(A) tail at the 3' end that prevents mRNA from ribonuclease digestion.
Hence, splicing leads to the removal of introns so that the mRNA can be translated into protein.

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