Membrane structure models: Which named model is accepted today as the correct description of biological membrane organization?

Introduction / Context:
Understanding membrane structure underpins cell transport, signaling, and compartmentalization. Several historical models existed, but the prevailing view is the Fluid Mosaic Model.

Given Data / Assumptions:

• Question asks for the currently accepted structural model of membranes.
• The Fluid Mosaic Model emphasizes lateral mobility and mosaic distribution of proteins.

Concept / Approach:
The Fluid Mosaic Model describes a dynamic lipid bilayer with embedded integral proteins and peripheral proteins, with carbohydrates attached as glycoproteins and glycolipids. This model accounts for fluidity, asymmetry, and protein mobility.

Step-by-Step Solution:
Identify valid membrane model → Fluid Mosaic. Exclude unrelated models (Lac Operon is gene regulation; Lock-and-Key is enzyme specificity). Select option emphasizing fluidity and mosaic proteins. Acknowledge refinements (rafts, cytoskeletal corrals) within the same framework.

Verification / Alternative check:
Experiments such as FRAP and freeze-fracture electron microscopy support lateral mobility and mosaic organization.

Why Other Options Are Wrong:
Page’s/Unit membrane static concepts lack modern dynamic features; Lac Operon and Lock-and-Key are unrelated topics.

Common Pitfalls:
Confusing general biology models with specific membrane models.

Final Answer:
Fluid Mosaic Model.