Question

Select the correct option with respect to post- transcriptional changes in eukaryotes?

1. 5' end - capping - addition of adenylate residues
2. 3' end - tailing - addition of methyl guanosine triphosphate
3. 3' end- tailing - addition of adenylate residues
4. 5' end- capping - addition of methyl guanosine triphosphate

• A. 1, 2, 3
• B. 3, 4
• C. 1, 2, 3, 4
• D. 1, 2

Answer 1

The correct option is B 3, 4

Transcription is the process where a single-stranded RNA is synthesised from a double stranded DNA.

The mRNA strand formed after transcription is called the primary transcript which undergoes post-transcriptional changes namely, capping, tailing and splicing.

Capping is the addition of methyl guanosine triphosphate to the 5’ end of primary transcript.

Tailing is the addition of adenylate residues at the 3’ end.

Capping and tailing takes place in eukaryotes for the following reasons:
• to protect the RNA from the action of ribonucleases (that brings about the breakdown of RNA)
• helps in attachment to ribosomes