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Question #46844
The Question
According to the fluid mosaic model, the quasi-fluid nature of lipids enables the lateral movement of proteins. In polarized columnar epithelial cells, tight junctions (zonula occludens) prevent the mixing of apical and basolateral membrane proteins. If a researcher treats these cells with a chemical that specifically depletes plasma membrane cholesterol, disrupting the localized rigid microdomains (lipid rafts) that anchor these junctions, which of the following will be the most direct consequence?
Options
- A.
Dissociation of tight junctions, resulting in the loss of cellular polarity due to the unrestricted lateral diffusion of apical and basolateral proteins.
- B.
Complete solidification of the plasma membrane, halting all lateral movement of integral and peripheral proteins across the cell.
- C.
Enhanced structural integrity of the zonula occludens, completely preventing the paracellular transport of water and ions.
- D.
Immediate detachment of the epithelial cells from the underlying basement membrane due to the rapid degradation of hemidesmosomes.
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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
Epithelial Junctions Polarity|Plasma Membrane Fluidity|Tight_Junction_Proteins
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize isolated facts: 'tight junctions stop leakage' and 'cholesterol provides membrane stability'.
The synthesis requires understanding that the membrane's inherent fluidity (Fluid Mosaic Model) constantly drives lateral protein movement.
Tight junctions act as physical barriers (fences) to this movement to maintain polarity.
The common misconception is assuming cholesterol removal makes the entire membrane rigid (Option B), whereas it actually destroys the localized rigid anchors (rafts), unleashing unrestricted lateral movement and causing polarity loss.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Structural Organisation in Animals - Class 11 |
| Concept | Epithelial Junctions Polarity |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |