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Plasma Membrane


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Plasma Membrane presentation

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Plasma Membrane

  1. 1. Plasma Membrane: The Gate Keeper Ms. Polson Biology October 18,2009
  2. 2. Plasma Membrane Lesson Objectives <ul><li>Students will be able to: </li></ul><ul><li>Use vocabulary related to transport across the plasma membrane </li></ul><ul><li>Differentiate between active and passive transport </li></ul><ul><li>Identify membrane structures that permit transport </li></ul><ul><li>Understand the function of the plasma membrane as a “gate keeper” </li></ul>
  3. 3. What is a Plasma Membrane? <ul><li>All living cells have them </li></ul><ul><li>Selective permeability </li></ul><ul><li>Asymmetric </li></ul><ul><li>Gives cell structure </li></ul><ul><li>Cell-cell recognition </li></ul><ul><li>Fluid mosaic model </li></ul><ul><ul><li>Lipid movement in bilayer </li></ul></ul><ul><li>Maintains homeostasis </li></ul>
  4. 4. Animal and Plant Plasma (cell) Membrane
  5. 5. Plasma Membrane Function <ul><li>Separate inside organelles from external environment </li></ul><ul><li>Regulate entrance and exit of substances </li></ul><ul><li>Transfer information </li></ul><ul><li>Establishment of electric potential difference </li></ul><ul><li>Site of biological activities </li></ul><ul><li>Attachment between cells </li></ul><ul><li>Removal of waste </li></ul>
  6. 6. Plasma Membrane Photograph: Cell Membrane
  7. 7. Plasma Membrane Structure <ul><li>Lipids </li></ul><ul><ul><li>Phosphlipids, Glycolipids, Steroids </li></ul></ul><ul><ul><li>Hydrophilic and hydrophobic properties </li></ul></ul><ul><ul><li>Gives flexibility </li></ul></ul><ul><li>Proteins </li></ul><ul><ul><li>Integral - transport channels </li></ul></ul><ul><ul><li>Peripheral - recognition sites </li></ul></ul><ul><ul><li>Determines membranes specific functions </li></ul></ul><ul><li>Sugars </li></ul>
  8. 8. Lipid Bilayer Model Cross Section <ul><li>Gorter and Grendel, 1925 </li></ul><ul><li>Two sheets of lipids </li></ul><ul><ul><li>7.5 nm thick </li></ul></ul><ul><li>Found around cell </li></ul><ul><li>Embedded with proteins </li></ul><ul><li>Strengthened with cholesterol molecules (animal) </li></ul>
  9. 9. Lipid Bilayer Model Phospholipid <ul><li>Hydrophilic </li></ul><ul><ul><li>Water loving </li></ul></ul><ul><ul><li>Phosphate end </li></ul></ul><ul><ul><li>Outside and inside </li></ul></ul><ul><li>Hydrophobic </li></ul><ul><ul><li>Water fearing </li></ul></ul><ul><ul><li>Lipid tail region </li></ul></ul><ul><ul><li>Center </li></ul></ul>
  10. 10. Plasma Membrane Hydrophilic and Hydrophobic
  11. 11. Passive Transport Simple Diffusion <ul><li>Result of inherent kinetic energy </li></ul><ul><ul><li>Thermal motion or heat </li></ul></ul><ul><li>No energy needed </li></ul><ul><li>Diffusion and osmosis </li></ul><ul><li>High concentration to low concentration: small molecules </li></ul><ul><ul><li>O 2 , CO 2 , H 2 O </li></ul></ul>
  12. 12. Simple Diffusion
  13. 13. Passive Transport Facilitated Diffusion <ul><li>Proteins act as tunnels </li></ul><ul><li>Carrier proteins help larger polar molecules cross membrane </li></ul><ul><ul><li>Glucose </li></ul></ul><ul><li>Moves materials along concentration gradient </li></ul>
  14. 14. Active Transport <ul><li>Energy is needed </li></ul><ul><li>Low concentration to high concentration </li></ul><ul><li>Movement of molecules up concentration gradient </li></ul><ul><li>Sodium-potassium pump </li></ul>
  15. 15. Active Transport <ul><li>Movement of large substances by vesicles </li></ul><ul><ul><li>Endocytosis – taking into cell </li></ul></ul><ul><ul><ul><li>Phagocytosis </li></ul></ul></ul><ul><ul><ul><li>Pinocytosis </li></ul></ul></ul><ul><ul><ul><li>Receptor mediate </li></ul></ul></ul><ul><ul><li>Exocytosis – expelling from cell </li></ul></ul><ul><ul><ul><li>ER or Golgi Apparatus </li></ul></ul></ul>
  16. 16. Types of Solutions <ul><li>Isotonic </li></ul><ul><ul><li>Concentration of dissolved substances are the same inside and outside the cell </li></ul></ul><ul><li>Hypotonic </li></ul><ul><ul><li>Concentration of dissolved substances are lower outside than inside </li></ul></ul><ul><li>Hypertonic </li></ul><ul><ul><li>Concentration of dissolved substances are higher outside than inside </li></ul></ul>
  17. 17. Homeostasis Plasma Membrane <ul><li>Maintains constant internal environment </li></ul><ul><li>Controls movement of materials in and out of the cell as a “gate keeper” </li></ul><ul><ul><li>Dynamic equilibrium </li></ul></ul><ul><li>Separates cellular organelles from external environment </li></ul>
  18. 18. Vocabulary Review <ul><li>Plasma Membrane </li></ul><ul><li>Homeostasis </li></ul><ul><li>Passive Transport </li></ul><ul><li>Simple Diffusion </li></ul><ul><li>Facilitated Diffusion </li></ul><ul><li>Active Transport </li></ul><ul><li>Hydrophilic </li></ul><ul><li>Hydrophobic </li></ul><ul><li>Endocytosis </li></ul><ul><li>Exocytosis </li></ul><ul><li>Isotonic </li></ul><ul><li>Hypertonic </li></ul><ul><li>Hypotonic </li></ul>
  19. 19. Questions… Comments… Thoughts?