Explain the process of RNAi and how it contributes to differential gene expression Solution RNA interference is a biological process in which RNA molecules inhibit gene expression of targeted mRNA. RNAi is mediated by two small RNA: miRNA and siRNA. these small RNA moleules bind to target mRNA and either increase or decrease their activity by inhibiting translation. This process is initiated by dicer enzyme that cleave long RNA strands into small double stranded siRNAs. so RNA unwound to yield two single stranded RNA molecules, of which one is called passenger strand and the other is guide RNA. Guide RNA is incorporated into RNA induced silencing complex (RISC). Guide RNA complementarily bind to mRNA moleule and then cleaved by argonaute-2, the catalytic component of RISC. Gene expression is maintained mainly by miRNA. miRNAs repress translation, involved in regulation of development, timing of morphogenesis, maintenance of stem cells..