Cell Transport

• The cell membrane is composed of a lipid bilayer that is selectively permeable
• Selectively Permeable - allows some substances to pass through but not others.
• Cholesterol molecules are only found in animal cells; more cholesteral = more rigid membrane
• Rate of Diffusion depends on concentration, temperature, surface area, size/mass of molecule, and distance of diffusion
• ions - electrically charged molecules
• osmotic pressure - force of the water pushing on the cell walls