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Multiple Choice
Which small molecule decreases the fluidity of the plasma membrane by interacting with phospholipids?
A
Glucose
B
Water
C
Cholesterol
D
Ethanol
Verified step by step guidance
1
Understand the structure of the plasma membrane: The plasma membrane is primarily composed of a phospholipid bilayer, which provides fluidity and flexibility to the membrane.
Identify the role of cholesterol in the membrane: Cholesterol is a lipid molecule that is interspersed within the phospholipid bilayer of the plasma membrane.
Analyze how cholesterol affects membrane fluidity: Cholesterol interacts with the fatty acid tails of phospholipids, which can either increase or decrease membrane fluidity depending on the temperature.
Consider the effect of cholesterol at physiological temperatures: At body temperature, cholesterol decreases membrane fluidity by restricting the movement of phospholipid fatty acid chains, thus stabilizing the membrane structure.
Conclude why cholesterol is the correct answer: Among the given options, cholesterol is the molecule that decreases the fluidity of the plasma membrane by interacting with phospholipids, unlike glucose, water, or ethanol.