Which of the following statements about eukaryotic mRNA processing is not correct?

a. the mRNA transcript must be exported from the nucleus.

b. a 5' cap and a 3' poly (A) tail must be added

c. the introns are removed

d. a 3' cap and a 5' poly (A) tail must be added

e. exons are spliced together to form the mRNA transcript

The correct answer will be option-D.

Explanation:

In eukaryotes, the process of transcription takes place inside the nucleus whereas translation takes place in the cytosol. So, mRNA has to export to the cytosol from the nucleus.

Before export, the post-transcriptional modification takes place like 5' capping, 3' tailing and splicing mechanism.

The capping is done at 5' end by adding modified guanine (G) nucleotide which protects the mRNA from exonuclease activity and tailing is done at 3' end by adding adenine nucleotides which provides stability to the mRNA. Splicing removes the junk DNA called introns and joins the exons before export.

Thus, option-D is the correct answer.