**1.1. Mechanism of the two prominent gene-silencing technologies**

The two technologies, however, vastly differ in their mode of action. RNAi uses small interfering RNA molecules to deplete target mRNAs by triggering their degradation and silencing- the gene. In RNAi, short, double-stranded RNA molecules, called small interfering RNAs- (siRNAs), bind to messenger RNAs (mRNAs) that bear complementary sequences, and blocks- the translation of protein encoded by the mRNA.-On the other hand, CRISPR/Cas9 system also- known as "molecular scissors" can introduce precise and targeted change within the genome.

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The technique involves designing specific "single guide RNAs" (sgRNAs) that recognize specific sequences in the genome known as PAM sites. Once the Cas9 proteins along with this- sgRNA are introduced into the cells, small deletions occur adjacent to the PAM site via doublestranded DNA breaks. The CRISPR/Cas9 system has been adapted to inhibit the expression of- single or multiple genetic loci wherein it cleaves specific DNA sequences, thereby rendering- the gene nonfunctional.
