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).
