The Cell Membrane • Aside from phospholipids, the cell or plasma membrane contains: • Proteins • Cholesterols • Glycoproteins (proteins with a carbohydrate side chain) • Glycolipids (lipids with a carbohydrate side chain)
The Cell Membrane Carbohydrate side chains Proteins Hydrophilic Region Hydrophobic Region Hydrophilic Region Phospholipid TEM of a red blood cell
The Cell Membrane and Transport The cell membrane is selectivelypermeable (only certain substances are allowed to pass through) All cells have a plasma membrane, including plant, animal, and bacteria.
CAN PASS THROUGH Things that can dissolve in fat Small molecules Water CAN NOT PASS THROUGH Things that can dissolve in water Large molecules Ions: Molecules with plus (+) or minus (-) charges CH2OH OH What can and can not pass through the membrane?
What are the 3 types of solutions? • There are 3 types of solutions: • Hypertonic • Hypotonic • Isotonic
What is an Isotonic Solution? • [Water] inside cell = [Water] outside cell • Cell is at equilibrium • Molecules are equally distributed in end • The amount of water entering the cell = the amount of water leaving the cell 95% water 95% water
What is a hypotonic solution? • A solution that has MORE water, and LESS solute • The cell can lyse or burst if left in a hypotonic solution 100% water 95% water
What is a hypertonic solution? • A solution that has LESS water and MORE solute • The cell will dehydrate 90% water 95% water
Which direction does water flow? • Water doesn’t flow at all. • Water flows from an area of low concentration to an area of high concentration. • Water flows from an area of high concentration to an area of low concentration.
Hypertonic Isotonic Hypotonic This type of passive transport is called osmosis.