1. Passive Transport Osmosis – Diffusion of water across a membrane –Diffusion = Movement of molecules from area of ________ concentration to area of ________ concentration. Which way will the water molecules move?

2. Diffusion of particals http://classwww.gsfc.nasa.gov/CAGESite/ pages/demo3.htmhttp://classwww.gsfc.nasa.gov/CAGESite/ pages/demo3.htm

3. Solute/Solvent A solute is added to the solvent Solute = stuff being put in –Solvent = stuff the solute is being added to (often a liquid like water) Concentration – number of molecules of something in a specific volume –You could think of it as solute/solvent –What would be the concentration of students in this room? Solute = ________________ Solvent = _______________ Concentration = _____/_____

4. 2 ways to think fluid movement: -water flows toward more solute -water flows down its concentration gradient Solvent Flow 1.Draw an arrow showing direction of water movement through the membrane. 2. Which side (A or B) will have a higher water level now? AB Salt compound

5. Hypertonic vs. Hypotonic Hypertonic = higher concentration of solute Hypotonic = lower concentration of solute These words can only be used together when comparing 2 solutions! Label the sides As Hypotonic or Hypertonic __________ ___________

6. Practice Problem Describe the flow of water using the words Hypotonic and Hypertonic.

7. Other than water Other molecules move down their concentration gradient just like water. But most other molecules can’t pass through a membrane freely (by themselves) –PROTEINS help

8. Passive transport Movement across a selectively permeable membrane that requires NO energy (ATP) Molecules move DOWN THEIR CONCENTRATION GRADIENT Simple diffusionFacilitated diffusion

9. Symport (cotransport) 2 different molecules are transferred together (same direction) across membrane –One with (down) its concentration gradient –One against its concentration gradient Gatorade!

10. Active Transport Molecules are pumped AGAINST concentration gradient Requires ENERGY –ATP Think of a bike pump

11. Antiport Molecules go opposite directions REQUIRES ENERGY – ATP! Both molecules go against their concentration gradient. Na+/K+ ATPase Almost all cells in your body use it

14. How they work together