Question

The poly a tail protects the 3’ end from____________

(a) 5’->3’ exonuclease

(b) 3’->5’ exonuclease

(c) Translation

(d) Export

I have been asked this question during an interview for a job.

I want to ask this question from Post-Transcriptional Modification in division Gene Expression : Transcription Prokaryotes of Cytogenetics

Answer 1

Correct choice is (b) 3’->5’ exonuclease

Explanation: The 3’ end of the RNA is susceptible to chewing by 3’->5’ exonucleases. So, the poly A tail acts as a safeguard which even if chewed partly will protect the valuable information of the RNA. This in place of inhibition rather promotes the next steps like transcription and export.