Cell Membrane Structure and Function

Phospholipid Structure and Function

• Phospholipids have a hydrophilic (water-soluble) glycerol backbone and two hydrophobic (water-insoluble) fatty acid tails.
• The hydrophobic tails face each other and form a bilayer.

Cellular Transport

• Lipid-soluble substances (e.g., O2, CO2, steroid hormones) can cross cell membranes because they can dissolve in the hydrophobic lipid bilayer.
• Water-soluble substances (e.g., Na+, Cl−, glucose, H2O) cannot dissolve in the lipid of the membrane.

Cell Membrane Components

• Integral proteins are anchored to, and embedded in, the cell membrane through hydrophobic interactions.
• Integral proteins may span the cell membrane and include ion channels, transport proteins, receptors, and GTP-binding proteins (G proteins).
• Peripheral proteins are not embedded in the cell membrane and are not covalently bound to membrane components.
• Peripheral proteins are loosely attached to the cell membrane by electrostatic interactions.

Learn about the structure and function of phospholipids and cell membranes, including how they regulate the transport of different substances.