According to the fluid mosaic model proposed by Singer and Nicolson (1972), what is the primary state and arrangement of the lipid bilayer?
Answer and explanation
Correct answer: A. Quasi-fluid phospholipid bilayer with embedded and peripheral proteins
- Step 1: The widely accepted Singer and Nicolson model defines the biological membrane as a quasi-fluid lipid bilayer.
- Step 2: The hydrophobic fatty acyl chains face inward to escape the aqueous cytosol, while hydrophilic polar heads face outward.
- Step 3: Proteins are present either as integral (embedded) proteins or peripheral (extrinsic) proteins that can drift laterally through the fluid bilayer.
Answer
Quasi-fluid phospholipid bilayer with embedded and peripheral proteins.
Why not the others: Rigid, immobile monolayer contradicts both the bilayer configuration and the lateral mobility of lipids; Solid protein sandwich corresponds to the outdated Danielli-Davson unit membrane hypothesis; Dynamic carbohydrate matrix misidentifies lipids as carbohydrates.
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