Question

Post-transcriptional modification of mRNA in eukaryotes is called
(a) Translation
(b) Splicing
(c) Sequencing
(d) Restriction

Answer 1

Hint: A mechanism involving the precise identification and excision of intervening sequences from between coding regions of transcribed pre-mRNAs is the post transcriptional modification of mRNA in eukaryotes.

Complete answer:
The primary transcript (the newly made RNA molecule) is not yet considered a messenger RNA when a eukaryotic gene is transcribed in the nucleus. It's an "immature" molecule called a pre-mRNA, instead.
To become a mature mRNA molecule that can escape the nucleus and be translated, the pre-mRNA has to go through some modifications. This includes splicing, capping, and adding a poly-A tail, both of which can potentially be controlled to result in a different product (accelerated, slowed down, or altered).

Three events include post-transcriptional modification of mRNA in eukaryotes.
- Splicing: deleting introns from the primary transcript and ligating exons to create a continuous sequence that determines a functional polypeptide.
- Capping of eukaryotic mRNAs: this refers to the addition to the 5' end of almost all eukaryotic mRNAs of 7-Methylguanosine in an unusual 5', 5’-triphosphate linkage.
- Tailing- Refers to 3'end cleavage and the addition of residues of 80 to 250 A to create a poly A tail.
RNA splicing is a form of RNA processing where a newly produced transcript is transformed into a mature messenger RNA ( mRNA) from a precursor messenger RNA (pre-mRNA). Introns (non-coding regions) are separated during splicing, and exons (coding regions) are fused together.
A multimega Dalton ribonucleoprotein complex known as the spliceosome performs splicing.
So, the correct answer is, ‘(b) Splicing’.

Note: In a cell's nucleus, DNA transcription occurs. In this process, the RNA that is synthesized is then transferred to the cytoplasm of the cell where it is converted into a protein. The RNA that is synthesized during DNA transcription is ready for translation into a protein in prokaryotes. However, eukaryotic RNA from DNA transcription is not ready for translation immediately. It is thus subject to regulation.