This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: membrane structure and function, Subject name: Biochemistry
[{'content': 'Transition temperature of lipid bilayers of cell membranes is increased by \nSelect and explain. \nA. Cholesterol, B. Saturated fatty acids, C. Unsaturated fatty acids, D. Hydrocarbons', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The cholesterol content of the membrane alters the fluidity of the membrane. When cholesterol concentration increases, the membrane becomes less fluid on the outer surface, but more fluid in the hydrophobic core. The effect of cholesterol on membrane fluidity is different at different temperatures. At temperature below the Tm, cholesterol increases fluidity and thereby permeability of the membrane. At temperatures above the Tm, cholesterol decreases fluidity.Ref: DM Vasudevan, page no: 11', 'role': 'assistant'}]