A mutation in a cell reduces the polarity of the phosphate headgroup on membrane phospholipids. Predict and analyze two likely effects on membrane structure and function.

• A. Reduced phosphate polarity would cause immediate crystallization of membranes into rigid cholesterol-like plaques that are then secreted from the cell unchanged.
• B. Decreased head polarity would reduce interactions with water and peripheral proteins, potentially decreasing membrane stability, impairing formation of bilayers and reducing function of membrane-associated enzymes and transporters.
• C. Decreased polarity would increase membrane water permeability and universally enhance function of all membrane-bound receptors due to improved lipid signaling rates.
• D. The mutation would convert phospholipids into triglycerides, prompting cells to use membrane lipids as bulk energy stores with no consequences for transport or signaling.

Answer: (B)