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Question #46720
The Question
In an E. coli culture grown in a medium with lactose as the sole carbon source, a targeted mutation completely inhibits the maturation of 16S rRNA. Despite the successful binding of allolactose to the repressor protein, the bacteria fail to metabolize lactose. Which of the following best explains this systemic failure?
Options
- A.
The smaller ribosomal subunit fails to bind to the polycistronic mRNA, preventing the translation initiation of the lac operon structural genes.
- B.
The 23S rRNA in the larger subunit loses its ribozyme activity, halting peptide bond formation during beta-galactosidase synthesis.
- C.
RNA polymerase is unable to bind to the lac promoter because the 16S rRNA is essential for the formation of the transcription initiation complex.
- D.
The repressor protein remains permanently bound to the operator region, preventing the transcription of the structural genes.
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
Ribosome Svedberg Coefficient|Lac Operon Inducibility|Ribosomal_Assembly
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often compartmentalize 'Gene Regulation' (Lac Operon) and 'Translation Machinery' (Ribosomes).
This question forces the synthesis of both concepts.
The primary trap is confusing the specific roles of different rRNAs (16S vs 23S) and distinguishing between transcription failure and translation failure.
The presence of the inducer ensures transcription happens, but the 16S mutation guarantees translation fails at the initiation step.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Cell – The Unit of Life - Class 11 |
| Concept | Ribosome Svedberg Coefficient |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |