How is the 3' end of a eukaryotic mRNA modified during RNA processing?

• A. It is spliced to remove introns.
• B. It is polyadenylated with a poly-A tail.
• C. It is methylated at the 5' end.
• D. It is capped with a 7-methylguanosine cap.

Answer: (B)

Verified step by step guidance

1. Understand that eukaryotic mRNA undergoes several modifications during RNA processing to become mature mRNA.
2. Recognize that the 3' end of the mRNA is specifically modified by the addition of a poly-A tail, a process known as polyadenylation.
3. Polyadenylation involves the enzymatic addition of a series of adenine nucleotides (A) to the 3' end of the mRNA molecule.
4. This poly-A tail is important for the stability of the mRNA, its export from the nucleus, and its translation efficiency.
5. Differentiate this process from other modifications such as splicing (removal of introns) and capping (addition of a 7-methylguanosine cap at the 5' end).