2. Activating Question!  Why does your home need to have walls?

3. Cellular Transport: The Movement of Materials

4. The Cell Membrane

5. Why does the cell need a membrane?  Why does your home need walls? Protect it from the environment Decide what can go in or out

6. Plasma Membrane ( aka the Cell Membrane)  Phosopholipid Bilayer  Called the Fluid Mosaic Model  Selectively Permeable (or semi-permeable)  What does this mean? (on next slide)

7. Why does the cell need a membrane?  The cell membrane …  Separates and protects cells from the outside environment  Decides what can enter or exit the cell

8. What it’s made of…  Membranes are made of a phospholipid bilayer (bi = two)

9. Phospholipids  Each phospholipid has a hydrophobic tail and hydrophilic head  Hydrophobic- water “fearing”  Hydrophilic – water “loving”

10. Phospholipid Bilayer  To keep the hydrophobic lipids away from water, phospholipids form a two-sided bilayer  Plasma membrane Plasma membrane WATER

11. Fluid Mosaic Model  The membrane also contains cholesterol, and proteins (with carbohydrate chains attached)  Cholesterol keeps the lipids from sticking together  Proteins move molecules across the membrane – carbohydrate chains help send signals/messages in cell interaction

12. Fluid Mosaic Model  The membrane is not this simple!  Fluid Mosaic Model Fluid Mosaic Model

13. Checkpoint!  How is the cell membrane like the walls of a house?

14. Checkpoint! A – Thumbs up & B – Thumbs down  Which part of this molecule is polar and hydrophilic: A or B?  Which part of this molecule is in the middle of the bilayer: A or B? A B

15. Checkpoint!  Why must the membrane be a bilayer?

16. Activating Question!  I plug in a Glade Plug-In at the front of the room…  Who will smell it first: the people at the back of the room or the people at the front of the room?  Will the people at the back of the room eventually smell it?

17. Selectively Permeable  Only certain things can pass through the membrane  Cells want to maintain homeostasis, stable internal conditions despite changes in its environment

18. Active (requires energy) Passive (no energy) Types of Transport

19. Osmosis Passive Simple Diffusion Facilitated Diffusion Passive Transport  Movement of materials from that does not require energy (ATP)

20. What is happening here???

21. High Concentration Low Concentration

22. Dynamic Equilibrium  Diffusion occurs so that there is an equal concentration of particles on both sides of the membrane

23. Types of diffusion:  Simple (diffusion) – diffusion across cell membrane  Facilitated diffusion - On next slide  Osmosis – the diffusion of water

24. Simple Diffusion  The passive movement of material straight through the cell membrane from an area of high concentration to an area of low concentration  Concentration- the amount of solute in a solution (ex. Salt in water)

25. Facilitated Diffusion  Diffusion of polar, hydrophilic particles that is helped by proteins in the membrane

26. Facilitated Diffusion  Polar and hydrophilic molecules cannot move through lipids, so they move through proteins  The molecules are still moving from high concentration to low concentration  Transport that does NOT require energy but does require the use of proteins in the membrane – still PASSIVE transport .

27. Diffusion vs. Facilitated Diffusion

28. Factors affecting diffusion  Concentration—diffusion always goes from high concentration to low concentration  Concentration gradient: when there is an uneven distribution of molecules (concentration) across the membrane  Temperature—the higher the temperature, the faster diffusion occurs  Molecular Size—the bigger the molecule, the longer diffusion takes  Diffusion Diffusion

29. Checkpoint!  Put 1 finger up for A. Put 2 fingers up for B.  Through diffusion, in which direction do particles move:  A- high concentration  low concentration  B- low concentration  high concentration

30. Checkpoint!  What is the end result of diffusion?

31. Checkpoint!  Will diffusion occur faster in boiling water or ice water?

32. Active Transport  Movement of materials from low concentration to high concentration  Uses a protein carrier that requires energy(uses ATP)  Particles move against the concentration gradient

33. Sodium-Potassium Pump  Mechanism of active transport that moves potassium ions (K+) into and sodium ions (Na+) out of the cell

34. Checkpoint!  Through active transport, in which direction do particles move:  A- high concentration  low concentration  B- low concentration  high concentration

35. Checkpoint!  In order to move Na+ and K- through the membrane, what is the energy that must be used?

36. Endocytosis  Process by which a substance enters a cell without passing through the membrane.  Intracellular vesicle is formed

37. Phagocytosis & Pinocytosis  Phagocytosis (Cell eating) - The process of membrane folding that enables cells to bring “food” into the cell  EX: White blood cells ingest bacteria  Pinocytosis (Cell drinking) - The process of membrane folding that enables cells to bring “water” (extracellular fluids) into the cell

38. Exocytosis  Process of moving particles out of a cell using extensions of the cellular membrane  how wastes are excreted from cells  Intracellular vesicle moves to plasma membrane and fuses with it to release wastes

39. Activating Question  Can you drink too much water? Explain.

40. Hyponatremia  Drinking too much water is called water intoxication, or hyponatremia, which means that your blood is too diluted and does not contain enough salt. Without the right balance of salt and water, your brain cells swell and burst, leading to death!  http://www.youtube.com/watch?v=WBXNCp dBFqQ http://www.youtube.com/watch?v=WBXNCp dBFqQ  How does your body maintain balance?

41. YES!  SACRAMENTO, Calif.- A woman who competed in a radio station’s contest to see how much water she could drink without going to the bathroom died of water intoxication.  Jennifer Strange, 28, was found dead in her suburban Rancho Cardova home hours after taking part in the “Hold Your Wee for a Wii” contest in which a radio station promised a Nintendo Wii video game system for the winner.

42. Osmosis  The diffusion of water through a selectively permeable membrane

43. Concentration Gradient  A difference in concentration on opposite sides of the cell  This makes diffusion and osmosis possible!

44. Osmosis-another look…  Tonicity – A measure of the solute concentration in a solution

45. Hypertonic Solution  Higher concentration of solute outside of the cell than inside  The water moves out of the cell into the solution, causing the cell to shrink

46. Hypotonic Solution  Higher concentration of solute inside the cell than outside the cell  Water moves from the solution into the cell, causing it to swell or burst (lysis)  Beneficial for plant cells – causes turgor pressure. In a hypotonic solution plants are turgid

47. Isotonic Solution  Equal concentration of solute on both sides of the cell  Water moves freely in to and out of the cell to maintain homeostasis.

48. Types of Solutions http://tonicitytonicity

49. Why doesn’t the plant cell undergo lysis?

50. Practice  In your table, draw what your cell would look like in each case. Use arrows to indicate the direction of water flow Effect of Osmosis on Cells Animal Cell SolutionBeforeAfter Isotonic Hypotonic Hypertonic

51. Explain what is happening in this cartoon…

52. Observations!  Take observations and draw the cells at the end of the video!  Red Blood Cells in Hypotonic Solution: http://www.youtube.com/watch?v=EA_ss8ZkjAM http://www.youtube.com/watch?v=EA_ss8ZkjAM  Red Blood Cells in Hypertonic Solution: http://www.youtube.com/watch?v=IRQLRO3dIp8 &feature=fvwrel http://www.youtube.com/watch?v=IRQLRO3dIp8 &feature=fvwrel