Question

Post-transcriptional processing adds a(n) ________ to the 3' end of the mRNA molecule.

A) poly A tail
B) exon
C) CAP
D) intron
E) poly C tail

Answer 1

In post-transcriptional processing, a poly A tail is added to the 3' end of the mRNA molecule, which provides protection from degradation and aids in mRNA export.

Step-by-step explanation:

Post-transcriptional processing adds a poly A tail to the 3' end of the mRNA molecule. This modification, which involves the addition of approximately 200 adenine residues, is carried out by an enzyme called poly-A polymerase after elongation is complete. The 3' poly-A tail serves multiple functions, such as protecting the pre-mRNA from degradation and assisting in the export of the mRNA from the nucleus to the cytoplasm.