Explain RNA interference (RNAi) mechanism.

Explain RNA interference (RNAi) mechanism.

• A. RNAi increases transcription by blocking repressors.
• B. RNAi uses single-stranded RNA to activate ribosomes.
• C. RNAi copies DNA sequences to create mutations.
• D. Double-stranded RNA triggers Dicer to produce siRNA/miRNA, which guide RISC to degrade or block translation of target mRNA.

Answer: (D)

RNA interference silences gene expression at the RNA level. When there is double-stranded RNA that matches a gene, an enzyme called Dicer cuts it into small interfering RNAs or microRNAs. These small RNAs join the RNA-induced silencing complex (RISC), and one strand serves as a guide to bring RISC to the target mRNA. If the guide pairs perfectly with the mRNA, an Argonaute protein in RISC cleaves the mRNA, leading to its degradation. If the pairing is imperfect, translation of the mRNA is blocked and the message becomes unstable. This combination—double-stranded RNA processed by Dicer into siRNA/miRNA, loading onto RISC, and guiding it to degrade or inhibit the target mRNA—best explains how RNA interference works.

RNA interference silences gene expression at the RNA level. When there is double-stranded RNA that matches a gene, an enzyme called Dicer cuts it into small interfering RNAs or microRNAs. These small RNAs join the RNA-induced silencing complex (RISC), and one strand serves as a guide to bring RISC to the target mRNA. If the guide pairs perfectly with the mRNA, an Argonaute protein in RISC cleaves the mRNA, leading to its degradation. If the pairing is imperfect, translation of the mRNA is blocked and the message becomes unstable. This combination—double-stranded RNA processed by Dicer into siRNA/miRNA, loading onto RISC, and guiding it to degrade or inhibit the target mRNA—best explains how RNA interference works.