GATE BT 2021 • Q27
MCQ • 1 Mark
Section 3: Genetics, Cellular and Molecular Biology
DNA replication, transcription, translation
Subtopic: Fundamentals of DNA replication, transcription, translation
Question Statement:
The cellular process which utilizes RNA-induced silencing complex to block
gene expression is
Options:
-
(A) RNA editing
-
(B) RNA interference
-
(C) RNA polyadenylation
-
(D) RNA splicing
Step-by-Step Solution & Explanation
### **Official Solution & Concept Analysis (GATE BT 2021 Q.27)**
**1. Governing Concept**:
- **Topic**: Molecular Genetics & RNA Interference (RNAi)
- **RNA Interference (RNAi)** is an evolutionary conserved post-transcriptional gene silencing mechanism where short double-stranded RNAs (siRNAs or miRNAs) are processed by Dicer and incorporated into the **RNA-Induced Silencing Complex (RISC)**. The guide strand directs RISC to complementary mRNA targets, causing target degradation or translation inhibition.
**2. Option Analysis**:
- **Option (A) [RNA editing] is INCORRECT**: Deamination mediated by ADAR/APOBEC cytidine/adenosine deaminases.
- **Option (B) [RNA interference] is CORRECT**: The specific cellular silencing pathway powered by the RISC complex.
- **Option (C) [RNA polyadenylation] is INCORRECT**: Mediated by poly(A) polymerase (PAP).
- **Option (D) [RNA splicing] is INCORRECT**: Mediated by the spliceosome (snRNPs).
**3. Final Answer**:
- **Correct Choice**: **B**
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