Diffusion, Osmosis & Active Transport

1. Diffusion, Osmosis & Active Transport Diffusion Osmosis

2. Diffusion The movement of molecules from an area of high concentration to an area of less concentration. • Perfume in the air

3. Diagram of food coloring diffusing in water.

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

5. Osmosis • The diffusion of water across a selectively permeable membrane. • Water crosses a selectively permeable membrane from a concentrated solution to a less concentrated solution

6. Osmosis http://www.usd.edu/~bgoodman/Osmos.htm

7. Osmosis in Red Blood Cells Hypertonic • If red blood cells float in water containing a lot of salt • there are fewer molecules of water in the “salt water” than in the blood cell • water moves out of the blood cells • the red blood cells shrink

8. Osmosis in Red Blood Cells Hypotonic • If red blood cells float in water containing very little salt • there are fewer molecules of water in the red blood cells than there are in the surrounding solution. • water moves into the blood cells • the red blood cells swell

9. Osmosis • a red blood cell is put in a glass of distilled water • because there is a higher concentration of water outside the cell, water enters the cell by OSMOSIS • too much water enters and the cell swells to the point of bursting open  • pieces of cell membrane are left in the water http://www.usd.edu/~bgoodman/Osmos.htm

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

11. Selectively Permeable Membrane • A membrane that allows only certain materials across • Materials pass through pores in the membrane

12. Passive Transport Net Diffusion Equilibrium • Passive Transport- the movement of materials through a cell membrane without energy • Diffusion and Osmosis

13. Selectively Permeable Membrane • This membrane is a complex structure • separates the contents of a cell from its surroundings • controls the movement of materials into and out of a cell through pores • interacts with the environment around a cell

14. Active Transport • Active Transport- the movement of materials through a cell membrane with energy • When a cell takes in a substance that is in higher concentration inside the cell than outside the cell

15. Methods of Active Transport • 1. Transport Proteins • in the cell membrane “pick up” molecules outside the cell and carry them in using energy ~~OR~~ • “pick up” molecules inside the cell and carry them outside using energy

16. Methods of Active Transport • 2. Transport by engulfing • The cell membrane surrounds (engulfs) a particle • An amoeba can engulf a smaller single celled organism

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

18. Why are osmosis & diffusion important?

19. Why are osmosis & diffusion important? • All living things must maintain homeostasis • Ability to maintain equilibrium by adjusting its processes at a cellular level • exchanging gases (usually carbon dioxide and oxygen) • taking in water, minerals & food • eliminating wastes.

20. Review Osmosis & Diffusion Here: http://wappingersschools.org/WJH/teachers/science/Jim_Site/asignments/cells/diffusionetc/diffusion_osmosis.html