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Question #45896
The Question
In a eukaryotic cell, a point mutation occurs exactly at the splice junction of a structural gene, preventing the spliceosome from recognizing the exon-intron boundary. Which of the following best describes the most likely consequence of this mutation during gene expression?
Options
- A.
RNA polymerase II will fail to transcribe the mutated sequence, resulting in the complete absence of the primary transcript (hnRNA).
- B.
Translation of the retained intron will likely introduce a premature stop codon or a frameshift, resulting in a non-functional, truncated polypeptide.
- C.
The ribosome will recognize the unprocessed intronic sequence and skip it during translation, producing a normal, functional polypeptide.
- D.
The mutation will be compensated by the wobble mechanism at the anticodon, ensuring the correct amino acid is still incorporated.
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
Spliceosome Mechanics|Insulin Chain Maturation|Alpha-1 Antitrypsin
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often assume that a 'point mutation' will only result in a single amino acid change (missense) or a single stop codon (nonsense).
However, when a point mutation hits a splice site, it disrupts RNA processing, causing massive downstream effects (frameshifts/truncation) due to intron retention.
The trap lies in confusing the specific roles of molecular machineries—assuming ribosomes can 'skip' introns (Option C) or that transcription itself is halted (Option A).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Molecular Basis of Inheritance - Class 12 |
| Concept | Spliceosome Mechanics |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |