RNA interference (RNAi) is a mechanism that inhibits gene expression at the stage of translation or by hindering the transcription of specific genes. RNAi targets include RNA from viruses and transposons (a form of innate immune response), and also plays a role in regulating development and genome maintenance. Small interfering RNA strands (siRNA) are key to the RNAi process, and have complementary nucleotide sequences to the targeted RNA strand. Specific RNAi pathway proteins are guided by the siRNA to the targeted messenger RNA (mRNA), where they “cleave” the target, breaking it down into smaller portions that can no longer be translated into protein.

the Rna interference basically produces a double stranded RNA molecule….since double stranded RNA is unstable..it degrades….hence we can control the mechanism of transcription and translation at any stage….:)