1. OSMOSIS! Class Notes Monday, Sept. 20, 2010

2. Remember: What is the difference between diffusion and osmosis? Diffusion is: the movement of molecules from where there are many to where there are few Happens in all cells! Osmosis is: Diffusionof WATER across a cell membrane

3. Osmosis Why is it important? Cells contain water molecules and most cells are surrounded by water molecules If cells aren’t surrounded by mostly pure water, water will diffuse OUT. 3 different types of osmosis: Hypertonic Hypotonic Isotonic

4. Hypertonic solution When more molecules of water leave the cell than enter

5. Hypotonic solution When more molecules of water enter the cell than leave

6. Isotonic solution Iso = “the same” When molecules of water are moving in and out of the cell in equal amounts