Plasma Membrane

1. Plasma Membrane

2. Phospholipid • Phospholipid Animations (3) Phospho head – polar Lipid tail - nonpolar

3. Phospholipid Bilayer • Hydrophilic heads (water-loving) Hydrophobic tails (water-hating)

4. Fluid Mosaic Model • BBC Education - AS Guru - Biology - Cells - Pathways - Plasma Membranes

5. Proteins in Membrane

6. Cholesterol: add stability to membrane in higher temperatures

7. Carbohydrate Chain

8. Carbohydrate Chain: Used as Identification Markers

9. PROTEIN JOBS: attaches to cytoskeleton

10. PROTEIN JOBS: • Enzymes which are catalytic teams for molecular assembly lines • A Biochemical Pathway (click on animation) • Biochemical Pathway Animation II (CLICK-ALSO CLICK ON ARROWS)

11. PROTEIN JOBS-Receptors: enable cells to detect chemical messages from other cells

12. PROTEIN JOB: Signal Transduction • Receptor binds to trigger a chain reaction • EXAMPLE ANIMATION (CLICK ON START AND NEXT) MAP Kinase Signal Transduction Animation by Dr. Vic Lemas at BioCreations • Another Signal Transduction Animation Interactive Concepts in Biochemistry - Interactive Animations

13. Signal Transduction Diagram

14. Diffusion • Movement of a substance from a region of higher concentration to a region of lower concentration

15. Diffusion • Scientific Method (diffusion animation)

16. Facilitated Diffusion • A protein helps the substance (like an ion) across the membrane

17. Facilitated Transport • Facilitated diffusion involves the use of a protein to facilitate the movement of molecules across the membrane.  • Cell Animations (scroll down to Carrier-mediated passive transport Facilitated transport)

18. Passive Transport • Cell does not need to use energy • Movement of molecules goes “down the gradient” (from high to low concentration) • Diffusion • osmosis • Facilitated diffusion

19. Active Transport • During active transport, cell needs to use energy (ATP) as molecules against a concentration gradient (low concentration to high concentration). • endocytosis • Exocytosis • Pumps (USE ATP) • Cell Animations (scroll down to active transport)

20. Comparing Active and Passive Transport • Shockwave Click here

22. Endocytosis • The process by which a cell engulfs material to bring it into the cell is called endocytosis. A vacuole is formed that contains the material that has been engulfed.

23. Exocytosis • Vesicle fuses with plasma membrane to exit the material outside the cell • (cell pooping)

24. Endocytosis Animation • Endocytosis and Exocytosis Animation • What is the difference between the two? Which brings material in and which brings materials out of the cell? • Endocytosis is in • Exocytosis is out

25. Diffusion: flow from high to low concentration • Also facilitated diffusion (protein channel)

26. Diffusion

27. Things that can pass freely through the plasma membrane • Hydrophobic molecules (oil soluble) • O2 • N2 • Nonpolar • Benzene • Small uncharged Polar  molecules  • H2O • CO2

28. Molecules that don’t pass through the phospholipid bilayer easily... • Large uncharged • Glucose • Polar molecules  • Sucrose • Ions (charged) H+ , Na+ , HCO3 , K+, Ca+2,Cl- , Mg+2

29. So what three characteristics of a molecule determine the permeability of the membrane? • Charge • Size • Polarity

30. However: some molecules which we would think should (or should not) cross the plasma membrane do - (or don't) because of the presence of the membrane proteins.

31. Osmosis • Osmosis is the movement of water from a region of high water concentration to a region of lower water concentration through a selectively permeable membrane. • The Cell: Passive Transport Osmosis - Learning - click

32. Solution Vocabulary Solution = solvent + solute Solute- what is being dissolved EX: salt Solvent –what is doing the dissolving EX: water

33. Osmosis • Scientific Method (animation)

34. Hypotonic Solution • Osmosis (click for animation) • A hypotonic solution is one that has less solute (more water). • Cells in hypotonic solution tend to gain water.

35. Isotonic Solution • Osmosis (click for animation) • the concentration of solute is the same on both sides of the membrane (inside the cell and outside). • A cell placed in an isotonic solution neither gains or loses water. Most cells in the body are in an isotonic solution.

36. Drag the bag • Osmosis (predict what will happen) • LabBench (do a little experiment)

37. Hypertonic Solution • Osmosis (click for animation) • A hypertonic solution is one that has a high solute concentration. • Cells in a hypertonic solution will lose water.

38. Plasmolysis • Plant cells placed in a hypertonic solution will undergo plasmolysis, a condition where the plasma membrane pulls away from the cell wall as the cell shrinks. • The cell wall is rigid and does not shrink. before

39. Osmosis Lab • Use grams on the scale. • Be very careful when carrying (use a spoon) and drying the egg (gently with a paper towel). • Two set-ups per lab table. (If one side breaks, you have a back-up.) • WHEN FINISHED: Clean beakers. Dry off scale and turn off.

41. Watch the • chloroplasts • Plasmolysis of Elodea • Also scroll down for rehydration of elodea

42. Plant Cell Plasmolysis Stiff Cell wall Plasmolysis: Flaccid: Turgid: Sunken in Normal pressure Lots of pressure Cell wall on cell wall on cell wall

43. Can you tell which is the plasmolyzed and which is normal elodea?

44. NORMAL CELL Compare Plant Cells Plasmolysis

45. water moves toward the area with a higher solute concentration because it has a lower water concentration.

46. water moves from hypotonic to hypertonic solution.

47. Red Blood Cells p. 83

48. If a cell is in a Hypotonic solution, the cell will… lose water If a cell is in a Hypertonic solution, the cell will… gain water Solutions

49. Turgor: pressure of water vacuole on the cell wall of a plant

50. Active Transport • Active Transport Animation • Cell needs energy to move particles “against the gradient” - from low to high concentration