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Question #47446
The Question
A researcher is studying a mammalian model for sensorineural hearing loss. They introduce a mutation that creates a functional restriction endonuclease cleavage site exactly within the promoter region of the gene coding for the motor protein of the outer hair cells in the Organ of Corti. If in vivo cleavage occurs at this site, which of the following represents the most likely physiological consequence and its correct molecular rationale?
Options
- A.
Loss of fine-tuned frequency discrimination because the cleavage destroys the RNA polymerase binding site, preventing transcription of the motor protein, while the auditory nerve remains intact.
- B.
Production of a truncated, non-functional motor protein because the restriction enzyme directly cleaves the mRNA transcript in the cochlear cytoplasm.
- C.
Normal hearing is preserved because the promoter region is not part of the structural gene, meaning the final amino acid sequence of the motor protein remains unchanged.
- D.
Complete deafness due to the inability of the auditory nerve to conduct action potentials, as the cleavage alters the reading frame of the structural gene.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Evolutionary_Exception
Tackle problems where standard rules evolve or change based on specific environmental constraints.
Concepts Behind This Question
Endonuclease|Prestin gene|Hair Cell differentiation
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between the functional roles of the promoter versus the structural gene in a transcriptional unit.
The trap relies on the common misconception that if a mutation does not alter the coding sequence (structural gene), the protein will remain normal (Option C).
It also tests the fundamental NCERT fact that restriction endonucleases act exclusively on DNA, not RNA (Option B), and links molecular loss-of-function to a specific sensory phenotype without nerve damage.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Neural Control and Coordination - Class 11 |
| Concept | Cochlear Frequency Coding |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |