Q.39 Match the terms in Group I with their associated functions in Group II.
| Group I | Group II |
|---|---|
| P. Shine-Dalgarno sequences Q. Leucine zipper R. Aminoacyl tRNA synthetase S. RNA interference (RNAi) | 1. Aminoacylation of tRNA 2. Gene silencing 3. Ribosome binding and facilitation of translation initiation 4. Transcription factors |
(A) P-3, Q-4, R-1, S-2
(B) P-4, Q-3, R-2, S-1
(C) P-2, Q-3, R-1, S-4
(D) P-3, Q-2, R-4, S-1
Correct Answer: (A) P-3, Q-4, R-1, S-2
Shine-Dalgarno sequences facilitate prokaryotic translation initiation by ribosome binding, leucine zippers enable transcription factor dimerization, aminoacyl tRNA synthetase performs tRNA charging, and RNAi silences genes post-transcriptionally. Option (A) correctly matches all functions.
Option Analysis
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(A) P-3, Q-4, R-1, S-2: Correct. Shine-Dalgarno (P) binds 16S rRNA anti-SD for translation initiation (3); leucine zipper (Q) mediates bZIP transcription factor dimerization (4); aminoacyl tRNA synthetase (R) catalyzes amino acid-tRNA esterification (1); RNAi (S) degrades target mRNA via RISC (2).
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(B) P-4, Q-3, R-2, S-1: Incorrect. Shine-Dalgarno not transcription factors (4); leucine zippers don’t facilitate translation initiation (3); aminoacyl synthetases unrelated to gene silencing (2).
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(C) P-2, Q-3, R-1, S-4: Incorrect. Shine-Dalgarno doesn’t silence genes (2); RNAi not transcription factors (4).
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(D) P-3, Q-2, R-4, S-1: Incorrect. Leucine zippers don’t silence genes (2); aminoacyl synthetases not transcription factors (4).
Shine-Dalgarno sequences, leucine zipper transcription factors, aminoacyl tRNA synthetase functions, and RNA interference mechanisms form critical Group I Group II matches in Q.39, testing molecular biology fundamentals for biochemical engineering exams.
Molecular Function Details
Shine-Dalgarno (AGGAGG) base-pairs with 16S rRNA 3′-CCUCCU-5′ positioning ribosomes at AUG start codons in prokaryotes. Leucine zippers form α-helical coiled-coils enabling bZIP proteins (Fos/Jun) to bind DNA TRE/AP-1 sites. Aminoacyl tRNA synthetases activate 20 amino acids, form aa-AMP intermediates, then transfer to cognate tRNA 3′-CCA yielding aa-tRNA for translation. RNAi pathways process dsRNA via Dicer to siRNA/miRNA guiding Argonaute/RISC for target mRNA cleavage or translational repression.
Matching Rationale
Prokaryotic translation specificity (P-3), eukaryotic transcription regulation (Q-4), universal translation charging (R-1), and post-transcriptional silencing (S-2) reflect distinct cellular compartments and mechanisms. Errors in B/C/D options confuse initiation with regulation processes.
Biotechnology Applications
These concepts underpin recombinant protein expression (Shine-Dalgarno optimization), metabolic engineering transcription factors, and RNAi-based gene knockdown in microbial strain development—directly relevant to bioreactor optimization and enzyme production pathways from prior Q.35-38 analyses.
