Small interfering RNA (siRNA) mediates gene silencing through which molecular mechanism?

• A Direct methylation of the target gene promoter region
• B Competitive inhibition of ribosomal peptidyl transferase activity
• C Inhibition of RNA polymerase II during transcription initiation
• D Base-pairing with complementary mRNA leading to its cleavage and degradation ✓

Explanation

siRNA is incorporated into the RISC complex, where the guide strand directs the complex to complementary mRNA sequences. Argonaute proteins within RISC cleave the target mRNA, leading to its degradation and post-transcriptional gene silencing. This is distinct from transcriptional silencing mechanisms.

Reference: Molecular Biology of the Cell, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.