Question

Which one of the following processes represents the dominance of the RNA-world?

• A. Splicing
• B. Capping
• C. Tailing
• D. All of the above

Answer 1

The correct option is A Splicing

Transcription is the process of synthesising RNA from DNA.

In eukaryotes, the primary transcript formed as a result of transcription is called heterogeneous nuclear RNA (hnRNA) and it undergoes certain changes called post-transcriptional changes which include capping, tailing and splicing.

The primary transcript or hnRNA has sequences that code for amino acids called exons, it also has sequences which do not code for amino acids called introns.

Such a transcript undergoes a process called splicing, where introns are removed and exons are linked. This process allows an efficient expression of the genes and produces useful or relevant proteins for survival.

Since splicing is exclusive to RNA, it empowers the RNA to remove the sequences that do not code for amino acids. Hence, the process of RNA splicing represents the dominance of the RNA-world.

The hnRNA also undergoes capping and tailing which protects it from the action of ribonucleases and helps in attachment to ribosomes.

Capping refers to the addition of methyl guanosine triphosphate at the 5’-end of heterogeneous nuclear RNA (hnRNA).

Tailing refers to the addition of adenylate residues (200-300) at the 3’-end of heterogeneous nuclear RNA (hnRNA).