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Diffusion, Osmosis, and Active Transport

Diffusion, Osmosis, and Active Transport. Diffusion. The movement of substances from an area of high concentration to an area of low concentration Random motion drives diffusion Equilibrium is reached when there is an even distribution of solute molecules Does NOT require energy.

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Diffusion, Osmosis, and Active Transport

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  1. Diffusion, Osmosis, and Active Transport

  2. Diffusion • The movement of substances from an area of high concentration to an area of low concentration • Random motion drives diffusion • Equilibrium is reached when there is an even distribution of solute molecules • Does NOT require energy

  3. Diffusion in Nature Evenly Distributed Concentrated

  4. Diffusion in Cells Nutrients Carbon Dioxide Wastes Oxygen

  5. Osmosis • The movement of water from areas of high water concentration to low water concentration. • Cells shrink or swell • Does NOT require energy

  6. Osmosis in Cells 98 % Water 2 % Salts 98 % Water 2 % Salts

  7. Osmosis in Cells 98 % Water 2 % Salts 95 % Water 5 % Salts

  8. Osmosis in Cells 98 % Water 2 % Salts 95 % Water 5 % Salts Movement of water out of cell to equilibrium results in shrinking of cell

  9. Osmosis in Cells 98 % Water 2 % Salts 100 % Water 0 % Salts

  10. Osmosis in Cells 98 % Water 2 % Salts 100 % Water 0 % Salts Movement of water into cell to equilibrium results in swelling of cell

  11. Effect of Water on Cells • Hypertonic Environment • High [solute], low [water] • Hypotonic Environment • High [water], low [solute] • Isotonic Environment • [water] = [solute] Hypotonic Hypertonic Isotonic

  12. Osmosis in Living Cells Cellulose in cell wall

  13. Effect of Osmosis on Red Blood Cells

  14. Osmosis in Plant Cells Elodea leaves exposed to salt water Elodea leaves exposed to distilled water Plasmolysis Hypotonic Hypertonic

  15. Passive Transport • Movement of molecules across a semi-permeable membrane • NO ENERGY REQUIRED

  16. Facilitated Diffusion • Movement of molecules across a semi-permeable membrane with a protein • The transport protein is specific for each kind of substance being transported • NO ENERGY REQUIRED

  17. Active Transport • The movement of materials from an area of LOW concentration to an area of HIGH concentration • Movement of molecules against the gradient • Opposite of Diffusion and Osmosis • Requires Energy! (ATP molecules)

  18. Active Transport • Movement of molecules across a semi-permeable membrane against a concentration gradient through a protein • ENERGY REQUIRED-ATP

  19. Active Transport in Paramecium • To maintain homeostasis, excess water must be pumped out of the cell against a concentration gradient by contractile vacuole Freshwater Paramecium

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