1. Essential Question: How do water and materials move in and out of cells? Diffusion Osmosis Facilitated Diffusion Active Transport Cell Transport

2. Cell Membranes Essential Question: How do cell membranes work?

3. Cell Membranes Function To enclose the cell and regulate what enters and exits Structure Lipid bilayer Contains embedded proteins a) channels b) pumps c) markers/signals

4. Cell Walls Function To protect and support the cell Structure Fibers of carbohydrate and protein – Ex: cellulose Porous – Water, gases, nutrients, etc. pass through easily

5. Cell Membrane vs. Cell Wall Membranes are semi-permeable: some substances can pass through but others cannot – Small: water, O 2, CO 2 – Large: proteins, carbs – “Selectively permeable”

6. A. Carbohydrate chain D. Lipid bilayer B. Protein marker E. Cytoplasm C. Extracellular fluid

7. Cell Transport Every living cell is surrounded by a liquid environment. In a solution, particles are always moving. Dissolved materials move across cell membranes in different ways.

8. Concentration concentration: mass / volume The amount of solute divided by the amount of solvent

9. Diffusion Movement of molecules from high to low concentration Continues until equilibrium: concentration is the same throughout Does not require energy Ex: air freshener Animation

10. Diffusion

11. Osmosis Diffusion of water through a selectively permeable membrane Continues until equilibrium is reached Does not require energy **Occurs when solute does not pass through membrane Ex: wrinkled fingers Animation

12. Osmosis

13. Osmosis in Living Cells Essential Question: How does osmosis affect your cells?

14. Solutions Hypertonic: having a higher concentration of solute (“above strength”) Hypotonic: having a lower concentration of solute (“below strength”) Isotonic: having equal concentrations of solute (“same strength”) Water moves from hypotonic to hypertonic solutions! SALT SUCKS!

15. Osmosis Ex: celery in water; salt on a slug

16. What happens when a living cell is placed into a solution? It depends on the solution!

17. When a cell is placed in a solution… Isotonic Concentration is the same as the cell Zero net water movement Animal CellPlant Cell

18. When a cell is placed in a solution… Hypotonic Concentration is lower than the cell Net water movement into the cell Animal CellPlant Cell

19. When a cell is placed in a solution… Hypertonic Concentration is higher than the cell Net water movement out of the cell Animal CellPlant Cell

20. Osmotic Pressure There is osmotic pressure on the hypertonic side of a membrane This is because water flows in the direction of more solutes SALT SUCKS! So then why don’t cells burst?  Animal cells – bathed in isotonic fluids  Plants & bacteria – cell walls

21. Facilitated Diffusion Diffusion through protein channels Used for large or charged particles that cannot pass through the membrane High to low concentration Does not require energy Ex: glucose, K + and Na +

22. Facilitated Diffusion

23. Active Transport Movement of particles from low to high concentration Does require energy!

24. Active Transport Carried out by: 1) Protein “pumps” in membrane Ex: Ca + 2) Endocytosis and exocytosis Ex: food and wastes

25. Endocytosis –Taking material into the cell by folding in the cell membrane and creating a vesicle Exocytosis –Releasing material out of the cell by fusing a vesicle with the outer membrane

26. Active Transport

27. Exocytosis