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Question #45222
The Question
A bacterial strain possesses a point mutation in the gene coding for Valyl-tRNA synthetase. This mutation alters the enzyme's catalytic domain, rendering it incapable of utilizing ATP to form the aminoacyl-adenylate intermediate. Despite the presence of abundant intracellular valine and all four degenerate codons for valine in the mRNA, which of the following best describes the fate of translation in this strain?
Options
- A.
Translation continues uninterrupted because the degeneracy of the genetic code allows other aminoacyl-tRNA synthetases to charge valine onto its cognate tRNAs.
- B.
Translation halts specifically at valine codons because the failure of the ATP-dependent activation step prevents the charging of all valine-specific tRNAs.
- C.
The ribosome utilizes the wobble position to recruit tRNAs charged with structurally similar amino acids, leading to a functional but altered polypeptide.
- D.
The uncharged valine tRNAs enter the ribosomal A-site, mimicking release factors and causing premature termination of the polypeptide chain.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
Aminoacyl_tRNA_Synthetase|Activation_Energy|Ribosome
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often confuse the redundancy of the genetic code (degeneracy) with the strict specificity of the charging enzymes.
While there are multiple codons and tRNAs for valine, there is typically only one Valyl-tRNA synthetase.
A mutation in this single enzyme creates a 'translation bottleneck' that degeneracy cannot bypass.
Another trap is assuming uncharged tRNAs act as release factors, confusing them with actual proteinaceous release factors.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biomolecules - Class 11 |
| Concept | Enzyme Activation Energy Lowering |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |