Diffusion & Osmosis

1. Diffusion & Osmosis

2. Define Diffusion

3. Diffusion • The movement of molecules from a area in which they are highly concentrated to a area in which they are less concentrated.

4. Draw a diagram of an example of diffusion we saw in class.

5. Draw a diagram of an example of diffusion we saw in class.

6. See an animation of diffusion here: http://lewis.eeb.uconn.edu/lewishome/applets/Diffusion/diffusion.html

7. Define osmosis

8. Osmosis • The diffusion of water across a selectively permeable membrane.

9. Define osmosis • Water moves from a high concentration of water (less salt or sugar dissolved in it) to a low concentration of water (more salt or sugar dissolved in it).  This means that water would cross a selectively permeable membrane from a dilute solution (less dissolved in it) to a concentrated solution (more dissolved in it). http://www.usd.edu/~bgoodman/Osmos.htm

10. Define osmosis http://www.usd.edu/~bgoodman/Osmos.htm

11. Define osmosis • In this picture a red blood cell is put in a glass of distilled water (all water with no salt or sugar in it).  Because there is a higher concentration of water outside the cell, water enters the cell by OSMOSIS.  In this case too much water enters and the cell swells to the point of bursting open.  In the end pieces of cell membrane are left in the water. http://www.usd.edu/~bgoodman/Osmos.htm

12. See an animation of osmosis here: http://lewis.eeb.uconn.edu/lewishome/applets/Osmosis/osmosis.html

13. Define selectively permeable membrane

14. Selectively Permeable Membrane • A membrane that allows only certain materials to cross it • Materials pass through pores in the membrane

15. For more information on diffusion & osmosis, click here: http://edtech.clas.pdx.edu/osmosis_tutorial/default.html

16. Why are osmosis & diffusion important?

17. Why are osmosis & diffusion important? • All living things have certain requirements they must satisfy in order to remain alive – maintain homeostasis • These include exchanging gases (usually CO2 and O2), taking in water, minerals, and food, and eliminating wastes. • These tasks happen at the cellular level. • Molecules move through the cell membrane by diffusion

18. Why are osmosis & diffusion important? • All living things have certain requirements they must satisfy in order to remain alive. These include exchanging gases (usually CO2 and O2), taking in water, minerals, and food, and eliminating wastes. These tasks ultimately occur at the cellular level, and require that molecules move through the membrane that surrounds the cell.

19. Why are osmosis & diffusion important? • This membrane is a complex structure that is responsible for separating the contents of the cell from its surroundings, for controlling the movement of materials into and out of the cell, and for interacting with the environment surrounding the cell.

20. Osmosis • If environment is: • Hypertonic: • MORE SOLUTES outside cell • MORE WATER IN CELL • over time, cell loses water and shrinks • Isotonic: • “Iso-” means environment “=” cell • No change in cell volume • Hypotonic: • LESS SOLUTES outside cell • LESS WATER IN CELL, more solutes in cell. • over time, cell gains water • HYPO—HIPPO

21. OSMOSIS ISOTONIC HYPOTONIC HYPERTONIC WATER WATER WATER WATER WATER WATER

22. OSMOSIS ISOTONIC HYPOTONIC HYPERTONIC WATER WATER WATER WATER WATER WATER

23. Shriveled RBCs Normal RBCs Swollen RBCs Osmosis Hypertonic Solution Isotonic Solution Hypotonic Solution Equal movement of waterinto and out of cells Net movement ofwater out of cells Net movement ofwater into cells