1. Passive Transport

2. Molecules can move across the cell membrane through passive transport. • There are 3 types of passive transport. • diffusion • osmosis • facilitated diffusion

3. Diffusion: Movement of molecules from an area of high to low concentration • Movement continues until equilibrium is reached • Equilibrium: same amount of molecules on the outside of a cell as the inside

4. Diffusion (contd) Where is the high Oxygen concentration? • Passive transport: No energy (ATP) required to move molecules • Molecule move down concentration gradients • C.G. = Difference in concentration from 1 area to another Where is the high CARBON DIOXIDE concentration?

5. O2 O2 O2 O2

6. O2 O2 O2 O2 O2 O2

7. O2 O2 O2 O2 O2 O2

8. Where is the HIGH oxygen concentration? O2 O2 O2 O2 O2 O2 Where is the LOW oxygen concentration?

10. O2 O2 O2 O2 O2 O2

11. O2 O2 O2 O2 O2 O2

12. Where is the HIGH oxygen concentration? Where is the LOW oxygen concentration? O2 O2 O2 O2 O2 O2 Cell X gets oxygen through the process of diffusion!

13. The reverse process is true w/ carbon dioxide. CO2 CO2 CO2 CO2 CO2 CO2 CO2 CO2 CO2

14. Where is the HIGH carbon dioxide concentration? CO2 CO2 CO2 CO2 CO2 CO2 CO2 CO2 CO2

15. CO2 CO2 CO2 CO2 CO2 CO2 CO2 CO2 CO2

16. CO2 CO2 CO2 CO2

17. Where is the HIGH carbon dioxide concentration? CO2 CO2 CO2 CO2

18. CO2 CO2 CO2 CO2 CO2 CO2 CO2 CO2

19. CO2 CO2 CO2 CO2

20. Defined: Diffusion of water from an area of high to low concentration High H20 concentration if: less particles dissolved in the water Low H20 concentration if: more particles dissolved in the water Osmosis

21. Dots represent dissolved particles (not water molecules)

22. Facilitated Diffusion • Defined: Larger molecules enter/exit with the help of protein channels in the plasma membrane • No energy is required • Q: Why are the molecules exiting this cell and not entering? • A: There are more molecules inside than out