Question

Which of the following describes how the mRNA undergoes a series of modifications after transcription?

• A. A GTP cap and a poly A tail are added to protect the mRNA as it leaves the nucleus.
• B. Splicing of the tRNA occurs to remove excess portions that will not be expressed during translation.
• C. Exons are spliced out from the mRNA and introns are spliced together to make a final mRNA transcript.
• D. Post-transcriptional editing of RNA is performed in both prokaryotes and eukaryotes depending on the gene that is being transcribed.

Answer 1

The correct option is A A GTP cap and a poly A tail are added to protect the mRNA as it leaves the nucleus.

Post-transcriptional modification of hnRNA in eukaryotes includes three events. Splicing is the removal of introns from the primary transcript and ligation of exons to form a continuous sequence specifying a functional polypeptide. Capping of eukaryotic mRNAs refers to the addition of 7-Methylguanosine to the 5’ end of almost all eukaryotic mRNAs in an unusual 5’,5’- triphosphate linkage where the 5' diphosphate end is attacked by the phosphorus atom of GTP molecule to add guanine residue at the 5’,5’- triphosphate linkage. Tailing refers to cleavage of 3’ end and the addition of 80 to 250 A residues to create a poly(A) tail. Thus, the correct answer is option A.