Q46.Enzymes involved in RNA interference are:
(1) Dicer
(2) Cohesin
(3) Bicoid
(4) Maskin
Dicer is the key enzyme directly involved in RNA interference (RNAi), processing double-stranded RNA into siRNA or miRNA for gene silencing. The correct answer for Q46 is (1) Dicer; the others are unrelated to RNAi.
Option Breakdown
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(1) Dicer: Correct. This RNase III enzyme cleaves long dsRNA or hairpin pre-miRNA into ~21-25 nt siRNA/miRNA duplexes, which load into RISC for mRNA degradation or translational repression.​
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(2) Cohesin: Incorrect. A protein complex (SMC1, SMC3, SCC1, SCC3) that holds sister chromatids together during mitosis/meiosis; involved in chromosome segregation, not RNAi.
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(3) Bicoid: Incorrect. A Drosophila morphogen (transcription factor) forming anterior-posterior gradients in embryos; regulates Hox genes like hunchback, unrelated to RNAi.
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(4) Maskin: Incorrect. A cytoplasmic polyadenylation element-binding protein (CPEB) interactor that regulates translation by binding eIF4E via cap structure; blocks translation initiation, not RNAi processing.
Why Only Dicer?
RNAi pathway: dsRNA → Dicer (cleavage) → RISC (Argonaute-mediated silencing). Others function in mitosis, development, or translation control, common CSIR NET distractors.​
Crack enzymes involved in RNA interference questions like Q46 for CSIR NET Life Sciences, GATE Biotech exams. Dicer is the sole RNAi enzyme here—it cleaves dsRNA into siRNA/miRNA for gene silencing via RISC. Learn why cohesin, bicoid, and maskin are distractors, with detailed functions, exam tips, and PYQ insights.
The diagram shows Dicer processing dsRNA/shRNA into siRNA for RISC, central to RNAi mechanism.
Core RNAi Enzymes
RNA interference silences genes post-transcriptionally using small RNAs.​
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Dicer: RNase III family; generates 21-25 nt duplexes with 3′ overhangs from dsRNA precursors.​
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Key partners (not options): Argonaute (RISC slicing), Drosha (miRNA nuclear processing).
Correct Answer: (1) Dicer
Only Dicer acts in RNAi biogenesis; others from unrelated pathways (cell cycle, embryogenesis, translation).​
Why Options Fail
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Cohesin: Loads via Scc2/4; acetylated for cohesion; mutations cause Cornelia de Lange syndrome.
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Bicoid: mRNA localized anteriorly; nuclear gradient activates zygotic genes.
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Maskin: Masks mRNA until CPEB phosphorylation releases eIF4E for polyadenylation/translation.
Exam Strategies
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RNAi core: Dicer + RISC (Argonaute); recall dsRNA → siRNA step.​
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Distractors: Dev. bio (bicoid), cell division (cohesin), translation (maskin).
