How do molecules of cholesterol affect the structure of cell membranes?

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1. Cholesterol molecules are interspersed within the phospholipid bilayer of cell membranes.
2. They help to modulate the fluidity of the membrane by preventing the fatty acid chains of the phospholipids from packing too closely together.
3. Cholesterol provides stability to the membrane by fitting into the gaps between phospholipids, thus reducing membrane permeability to small water-soluble molecules.
4. At high temperatures, cholesterol helps to maintain membrane integrity by preventing the membrane from becoming too fluid.
5. At low temperatures, cholesterol prevents the membrane from becoming too rigid by disrupting the regular packing of phospholipids.

Key Concepts

Cholesterol Structure and Function

Cholesterol is a lipid molecule with a complex ring structure that plays a crucial role in cell membranes. It helps to maintain membrane fluidity by preventing the fatty acid chains of phospholipids from packing too closely together, which is essential for proper membrane function and flexibility.

Membrane Fluidity

Membrane fluidity refers to the viscosity of the lipid bilayer of cell membranes, which affects how proteins and lipids move within the layer. Cholesterol contributes to this fluidity by acting as a buffer; it stabilizes the membrane at high temperatures and prevents it from becoming too rigid at low temperatures.

Phospholipid Bilayer

The phospholipid bilayer is the fundamental structure of cell membranes, composed of two layers of phospholipids with hydrophilic heads facing outward and hydrophobic tails facing inward. Cholesterol intersperses within this bilayer, influencing its properties and the overall integrity of the membrane.