Question

What happens to exons and introns in splicing?

Answer 1

Introns:

1. A segment of DNA or RNA that does not code for proteins is known as an intron.
2. Introns interrupt the sequence of genes.
3. Introns act as hot spots for the recombination.

Exons:

1. Nucleic acid coding sequences present on mRNA are known as exons.
2. Exons are highly conserved sequences.
3. Exons do not change frequently with time.

RNA splicing:

1. It is the process by which the newly synthesized pre-mRNA, also called as hnRNA, (heterogeneous nuclear RNA) is processed and forms mature mRNA.
2. hnRNA is processed inside the nucleus and then converted to mRNA, which then comes to the cytoplasm and undergoes either translation or protein synthesis.
3. It is known as a post-transcriptional modification.
4. If an intron is not removed during the splicing in mRNA, it will lead to the formation of non-functional or altered protein as a result of translation.
5. In the RNA splicing process, the non-coding intervening regions known as ‘introns’ are removed and the coding regions called as ‘exons’ are joined together.
6. Spliceosome then catalyzes the RNA splicing process. Ribozymes (catalytic RNA) are capable of catalysing their own splicing.
7. Additionally, 5’ capping with the modified Guanine nucleotide and tailing with Poly-A (Adenylate) residues at 3’ end is done to protect coding segments and to provide stability to mature mRNA.