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Movement Across the Membrane

Movement Across the Membrane. Active and Passive. Diffusion. is the movement of molecules from a region of high concentration to a region of less concentration Diffusion Animation Click to remove the lid to see the spontaneous movement. Concentration Gradient.

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Movement Across the Membrane

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  1. Movement Across the Membrane Active and Passive

  2. Diffusion • is the movement of molecules from a region of high concentration to a region of less concentration • Diffusion Animation Click to remove the lid to see the spontaneous movement

  3. Concentration Gradient • Movement of molecules from regions of high concentration to regions of low concentration

  4. Passive Transport No energy by the cell Diffusion Osmosis Facilitated Diffusion Active Transport Energy by the cell active pumps Movement

  5. Semipermeable Membranes • allow some things to pass through them but prevent other things from passing through.

  6. Which way will the water go? • Impermeable= = permeable

  7. OSMOSIS • Is the diffusion of water through a semipermeable membrane. • Diffusion and Osmosis Animations

  8. Will Allow oxygen water Carbon Dioxide Ammonia glucose, amino-acids Will NOT Allow larger molecules like Sucrose Starch protein Semipermeable to what? Move freely

  9. Selectively Permeable

  10. Osmosis Animation • Osmosis Demonstration • What is happening to the Water? (blue) • What is the difference between the dissolved substances red and green?

  11. Types of Solutions • Isotonic: The solutions being compared have equal concentration of solutes. • Hypertonic: The solution with the higher concentration of solutes. • Hypotonic: The solution with the lower concentration of solutes.

  12. Types of Solutions • Isotonic, hypertonic, and hypotonic solutions animations

  13. DO WORKSHEET OF Red Blood Cells • (Drop Cell into solution animation) and Osmometer, then click on this animation Osmometer en Francais (refer to worksheet)

  14. With Red Blood Cells • Hypotonic Isotonic Hypertonic

  15. Osmosis Animation • Osmosis Animation Click to view movies, replay

  16. Some Common Examples of Osmosis • Absorption of water by plant roots. • Reabsorption of water by the proximal and distal convoluted tubules of the nephron. • Reabsorption of tissue fluid into the venule ends of the blood capillaries. • Absorption of water by the alimentary canal — stomach, small intestine and the colon.

  17. Equilibrium No Net change in the flow of water in and out

  18. Elodea (Anacharus) • Common Aquarium Plant • Leaves are one cell thick

  19. Cell Wall Permeability • The cell wall, although strong and rigid, is completely permeable to water and dissolved minerals. • Most green plants do not have woody stems to hold them up, but depend on cell turgor - the stiffness given to cell walls by being full of water - to give them rigidity.

  20. Unlike animal cells, plant cell have a cellulose cell wall surrounding the cell membrane

  21. The turgid cells in turn press against the packing tissue or cortex of the plant stem - giving stiffness to the stem and holding the plant upright. As the cells lose water their internal pressure drops and they lose shape, becoming flaccid. The plant will droop and wilt. Turgid vs. Flaccid

  22. Stained Water Vacuoles Flaccid Plant Cells (or plasmolysed) Turgid Plant Cells

  23. Elodea

  24. Osmosis in Elodea

  25. Were you right?

  26. Passive Transport • Does not require energy

  27. No Energy Required

  28. Facilitated Diffusion

  29. Facilitated Diffusion • Protein Channels that allow specific substances to pass through • carrier protein for glucose • can also be other channels for ions

  30. Active Transport • Molecules moved across the membrane “against the gradient” (from low concentration to high concentration) • This requires the cell to expend energy • Active Transport Animation

  31. Active Transport(against the gradient)-Lo to Hi Concentration • Fewer on outside • More on inside, but will move in Uses Energy

  32. Sodium Potassium Pump • Sodium Potassium Pump and Proton Pump animations • NOTE THAT THESE ARE EXAMPLES OF ACTIVE TRANSPORT (require the cell to use ATP)

  33. Contrast

  34. Endocytosis/exocytosis

  35. Endocytosis • Bringing food in by pinching off the membrane

  36. Phagocytosis

  37. Pinocytosis Cell engulfs small, liquid molecules.

  38. Receptor Mediated Macromolecules bind to receptors on the surface of the cell. Receptors with bound macromolecules aggregate in one area and are brought into the cell by endocytosis.

  39. Exocytosis • Pinching off the membrane to remove wastes “Cell pooping” • Exocytosis Animation

  40. REVIEW ANIMATIONS • Transport Across Membrane Animations • Excellent Endo and Exo Video Clips

  41. REVIEW PICTURES • MEMBRANE TRANSPORT QUIZ

  42. What is this?

  43. What type of membrane transport?

  44. What is this showing?

  45. Why is the water moving in?

  46. Why is the water moving out?

  47. Will the water in the cell in the diagram at left flow out, in, or in and out equally?

  48. What has happened to this cell?

  49. What is this called?

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