Question

Describe how RNAi works, and explain how RNAi is involved in post transcriptional regulation.

Answer 1

RNAi = RNA interference
It is a protective mechanism found exclusively in eukaryotes.
It provides protection against invading RNA genome-containing viruses.

In eukaryotes, the genome is double stranded RNA and it is located in the nucleus.
The RNA is generally dingle-stranded and is found in the cytoplasm.
If there is a double stranded RNA found in the cytoplasm, it indicates an infection.
The recognition of a dsRNA triggers the activation of the RISC compelx.
RISC = RNA-induced silencing compelx
The activated RISC compelx binds to the dsRNA and mediates its cleavage.
It is a post-transcriptional regulatory mechanism i.e. it regulates gene expression after the transcription event.