Question

Which of the following contains the three posttranscriptional modifications often seen in the maturation of mRNA in eukaryotes?

A. 5′-capping, 3′-poly(A) tail addition, splicing
B. 5′-poly(A) tail addition, insertion of introns, capping
C. 3′-capping, 5′-poly(A) tail addition, splicing
D. removal of exons, insertion of introns, capping
E. heteroduplex formation, base modification, capping

Answer 1

The correct answer to the question of the three posttranscriptional modifications in eukaryotic mRNA maturation is A. 5′-capping, 3′-poly(A) tail addition, and splicing. These modifications are essential for the stability and functionality of the mature mRNA.

Step-by-step explanation:

The three posttranscriptional modifications often seen in the maturation of eukaryotic mRNA are:

1. The addition of a 5′-capping, where a 7-methylguanosine cap is added to the 5′ end of the growing transcript.
2. 3′-poly(A) tail addition, in which the pre-mRNA is cleaved and then extended with a chain of adenine nucleotides following the cleavage site.
3. Splicing, which involves the removal of introns and joining of exons to form the continuous coding sequence that will be translated into protein.