7 3 movement through

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7 3 movement through

  1. 1. 7-3 Movement through the Membrane <ul><li>Identify the main functions of the cell membrane. </li></ul><ul><li>Describe what happens during diffusion </li></ul><ul><li>Explain the processes of osmosis, facilitated diffusion, and active transport. </li></ul>
  2. 2. Cell Membrane <ul><li>Regulates what enters and leaves the cell </li></ul><ul><li>Provides protection and support </li></ul><ul><li>The core is a double-layered sheet called a lipid bilayer </li></ul>
  3. 4. Diffusion <ul><li>Movement of substances from an area of higher concentration to an area of lower concentration </li></ul><ul><li>Equilibrium – all areas of concentration are equal </li></ul>
  4. 5. Diffusion (cont.) <ul><li>Diffusion is passive – it does NOT require cellular energy to take place </li></ul><ul><li>Molecules move along the “concentration gradient” </li></ul>High Concentration Low Concentration
  5. 6. Osmosis <ul><li>Most biological membranes are “selectively permeable” </li></ul><ul><ul><ul><li>Only allow certain substances through </li></ul></ul></ul>
  6. 7. How Osmosis Works <ul><li>In a sugar-water solution: </li></ul><ul><ul><li>Cell membranes are permeable to water but impermeable to sugar </li></ul></ul><ul><ul><li>To reach equilibrium, which all cells “want” to do…water moves toward the side of the membrane with the higher concentration of solute (sugar) molecules </li></ul></ul><ul><ul><li>See fig. 7-17, pg. 186 </li></ul></ul>
  7. 8. Osmotic Pressure
  8. 9. Osmotic Pressure (cont.)
  9. 10. Osmotic Pressure (cont.)
  10. 11. Facilitated Diffusion <ul><li>Moves molecules across the membrane that can’t pass by diffusion through special protein channels </li></ul><ul><li>Ions, sugars, salts </li></ul>
  11. 12. Active Transport <ul><li>Requires energy to move particles against the concentration gradient </li></ul>Takes Energy!
  12. 13. Active Transport (cont.) <ul><li>Sodium-Potassium Pump and Coupled Channels </li></ul>
  13. 14. Endocytosis <ul><li>Moves LARGE particles into the cell </li></ul><ul><li>Phagocytosis - amoeba </li></ul>
  14. 15. Exocytosis <ul><li>Moves large particles to the outside of the cell </li></ul><ul><li>“ ex it” – “ ex ocytosis” </li></ul>
  15. 16. Section Review <ul><li>What processes are made possible by the cell membrane? </li></ul><ul><li>How does diffusion affect cells? </li></ul><ul><li>Describe how water moves during osmosis. </li></ul><ul><li>What is the basic structure of a cell membrane? </li></ul><ul><li>How does active transport differ from diffusion? </li></ul>

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