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Question #45905
The Question
Alpha-1 antitrypsin (AAT) is a therapeutic protein used to treat emphysema. Suppose a mutation severely compromises the proofreading fidelity of the specific aminoacyl-tRNA synthetase responsible for charging tRNAs during AAT synthesis. Which of the following best describes the primary cellular and systemic consequences of this molecular error?
Options
- A.
Synthesis of misfolded AAT polypeptides that aggregate in the endoplasmic reticulum of hepatocytes, causing liver damage and subsequent alveolar wall degradation due to AAT deficiency in the lungs.
- B.
Failure of the AAT mRNA to bind to the smaller subunit of the ribosome, preventing translation initiation and leading to immediate apoptosis of lung cells.
- C.
Incorporation of incorrect amino acids leading to misfolded AAT that aggregates directly in the alveoli, physically destroying the respiratory surface area.
- D.
Uncharged tRNAs entering the A-site of the ribosome, causing premature termination of the polypeptide chain and accumulation of defective mRNA in the nucleus.
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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
tRNA synthetase|Alpha-1 Antitrypsin|Endoplasmic Reticulum Stress
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot & Location Trap: Students learn in NCERT Biotechnology that AAT is used to treat emphysema (a lung disease).
Therefore, they intuitively associate any AAT defect directly with lung tissue aggregation (Option C).
The critical NCERT-Plus synthesis requires understanding that AAT is synthesized in the liver; thus, translational errors (tRNA mischarging) cause protein aggregation in the hepatocyte ER, while the lung suffers from a deficiency of the functional protein, not an accumulation of the defective one.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Molecular Basis of Inheritance - Class 12 |
| Concept | tRNA Charging Accuracy |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |