Question

Double stranded RNA is cleaved by a nuclease called as Dicer and small fragments are generated that are known as _______.

• A. short interspersed RNAs
• B. long interspersed RNAs
• C. small interfering RNAs
• D. long interfering RNAs

Answer 1

The correct option is C small interfering RNAs

RNAi is a conserved biological response to double-stranded RNA that mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes. This is called gene silencing or co-suppression or post-transcriptional gene silencing, it is a sequence-specific gene regulation resulting in the inhibition of translation.

The very first step of RNAi involves processing and cleavage of longer double-stranded RNA (dsRNA) or pri-miRNA into small interfering RNAs (siRNA) and microRNA respectively, by the action of endoribonuclease enzyme called Dicer. When siRNA are formed they are bound by a multiprotein component complex, which discards one strand to form an activated complex containing the guide or antisense strand. This activated antisense strand then binds to an mRNA bearing the complementary sequence and inactivates its expression.