2. Movement through a Membrane- Passive Transport

3. Membranes 3 Types 1.Permeable –Anything can move through 2.Impermeable –Nothing can move through 3.Semi permeable –Some can move through, some cannot

4. How things get in? Diffusion: – the tendency of molecules to move from areas of high concentration to areas of low concentration (across cell membrane) Concentration: how many molecules are in a given space

5. Which is high concentration and which is low? = a molecule High ConcentrationLow Concentration

6. Which direction will the molecules move?

7. What causes diffusion? Molecules move all the time! Motion is random Molecules run into each other  move to where there are less molecules This process requires no energy Think: if keep packing people into the room, door opens, where will people try to go?

8. This random motion results in predictable movement The molecules always move from areas of… to areas of… High Concentration Low Concentration

9. What does all this have to do with biology? Diffusion is one of the ways materials pass through cell membranes! We will be working on a lab that explores this concept

10. Osmosis Movement of water from concentration to concentration (across cell membrane). Movement of anything else?

11. Effects Cell 3 Ways Hypertonic Solution: Water moving out of cell. Cell getting? Hypotonic Solution: Water moving into the cell. Cell getting? Isotonic Solution: Water not moving. Why? Cell size?

12. Do you really know Passive Transport? Tape down in today’s through What is going to happen in each case?