Movement across membrane

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Movement across membrane

  1. 1. movement of substances across the plasma membrane
  2. 2. what are the substances needed by the cells? how the needed substances move into the cells?
  3. 3. Substances needed by the cells <ul><li>Water </li></ul><ul><li>Oxygen </li></ul><ul><li>Nutrient </li></ul><ul><ul><li>Glucose </li></ul></ul><ul><ul><li>Amino acid </li></ul></ul><ul><ul><li>Mineral </li></ul></ul><ul><ul><li>Fatty acid </li></ul></ul><ul><ul><li>Vitamin </li></ul></ul><ul><ul><ul><ul><ul><li>The substances have to move across the membrane </li></ul></ul></ul></ul></ul>
  4. 4. Substances to be eliminate from the cells <ul><li>Carbon dioxide </li></ul><ul><li>Urea </li></ul><ul><li>Toxin </li></ul>
  5. 5. plasma membrane structure
  6. 6. Fluid Mosaic Model <ul><li>1972 - Singer and Nicolson called the membrane a “Fluid Mosaic Model”. </li></ul><ul><li>Mosaic: different proteins embedded in the phospholipids. </li></ul><ul><li>Fluid: proteins and phospholipids can move freely in the membrane. </li></ul>
  7. 10. <ul><li>Components of a phospholipid bilayer. </li></ul><ul><li>1. phospholipids </li></ul><ul><li>2. proteins - enzymes, receptors, transport. </li></ul><ul><li>3. glycolipids </li></ul><ul><li>4. glycoproteins </li></ul><ul><li>5. carbohydrates </li></ul><ul><li>6. cholesterol </li></ul>
  8. 11. Plasma Membrane <ul><li>Boundary that separates the living cell from it’s non-living surroundings. </li></ul><ul><li>Phospholipid bilayer </li></ul><ul><li>Amphipathic - having both: </li></ul><ul><li>hydrophilic heads </li></ul><ul><li>hydrophobic tails </li></ul><ul><li>~8 nm thick </li></ul>Phospholipid
  9. 15. <ul><li>Controls traffic into and out of the cell with phospholipids and transport proteins . </li></ul><ul><li>Selectively permeable </li></ul><ul><li>>>> semi-permeable </li></ul>function Transport protein
  10. 16. What is Selective Permeability? <ul><li>The property of biological membranes which allows some substances to cross more easily than others. </li></ul>
  11. 17. Transport Proteins <ul><li>Transports molecules or ions across biological membranes </li></ul><ul><li>Two types: </li></ul><ul><ul><li>Carrier proteins </li></ul></ul><ul><ul><li>Pore proteins </li></ul></ul>
  12. 18. Through phospholipids layer: Non polar molecules = Oxygen. Carbon dioxide, water , lipid soluble molecules By pore – proteins : water soluble molecules and ions By carrier- proteins and energy : ions. By carrier- proteins : glucose, amino acids.
  13. 19. <ul><li>Passive transport: NO energy is expended. </li></ul><ul><ul><li>Simple diffusion – gases, </li></ul></ul><ul><ul><li>Osmosis – water </li></ul></ul><ul><li>facilitated diffusion : </li></ul><ul><li>type of passive transport which uses transport proteins. </li></ul><ul><li>– glucose and amino acid </li></ul><ul><li>Active transport : </li></ul><ul><ul><li>Using carrier protein and energy – ions </li></ul></ul>Movement of substances
  14. 20. Diffusion The net movement of a substance (molecules) down a concentration gradient from an area of high con centration to an area of low concentration .
  15. 23. Example:
  16. 26. Facilitated diffusion <ul><li>Allows diffusion of large, membrane insoluble compounds such as sugars and amino acids </li></ul><ul><li>Does not require energy (passive) </li></ul><ul><li>Highly Selective </li></ul><ul><li>Substance binds to transport protein </li></ul><ul><li>Fully reversible - molecules may enter the cell and leave the cell through the transport protein. </li></ul><ul><li>Particles move from areas of high concentration to areas of low concentration. </li></ul><ul><li>Movement rate of particles will saturate </li></ul><ul><ul><li>Maximum rate limited by number of transporters </li></ul></ul><ul><ul><li>Once all transporters are operating at 100%, an increase in concentration will not increase rate </li></ul></ul>
  17. 29. Active Transport <ul><li>Movement across membrane with an energy cost (usually against concentration </li></ul><ul><li>Used to pump specific compounds in or out of the cell </li></ul><ul><li>Requires energy to overcome the concentration gradient or to allow a large or charged particle to cross membrane </li></ul><ul><li>Requires specific carrier proteins </li></ul><ul><ul><li>The energy requirement distinguishes active transport from facilitated diffusion </li></ul></ul>
  18. 32. Osmosis <ul><li>The movement of water across selectively permeable membranes . </li></ul><ul><li>The water moves from a low concentration area to high concentration area </li></ul>
  19. 37. Cell membranes are completely permeable to water, therefore, the environment the cell is exposed to can have a dramatic effect on the cell.
  20. 40. Hypotonic solution <ul><li>Less solute </li></ul><ul><li>More water </li></ul><ul><li>Compare to cytoplasm of the cell </li></ul>
  21. 41. Hypertonic solution <ul><li>More solute </li></ul><ul><li>Less water </li></ul><ul><li>Compare to cytoplasm of the cell </li></ul>
  22. 42. Isotonic solution <ul><li>Equal concentration compare to cytoplasm of the cell </li></ul>
  23. 43. <ul><li>Hypertonic Solution : </li></ul><ul><li>Solute concentration of solution higher than cell </li></ul><ul><ul><ul><li>More dissolved particles outside of cell than inside </li></ul></ul></ul><ul><ul><ul><li>of cell </li></ul></ul></ul><ul><ul><li>Hyper = more (think hyperactive); Tonic = </li></ul></ul><ul><ul><li>dissolved particles </li></ul></ul><ul><ul><li>Water moves out of cell into solution </li></ul></ul><ul><ul><ul><li>Cell shrinks </li></ul></ul></ul>
  24. 44. <ul><li>Hypotonic Solution : </li></ul><ul><li>Solute concentration of solution lower than cell </li></ul><ul><ul><li>Less dissolved particles outside of cell than inside of cell </li></ul></ul><ul><ul><li>Hypo = less, under (think hypodermic, hypothermia); </li></ul></ul><ul><ul><li>Tonic = dissolved particles </li></ul></ul><ul><ul><li>Water moves into cell from solution </li></ul></ul><ul><ul><li>Cell expands (and may burst) </li></ul></ul>
  25. 45. <ul><li>Isotonic Solution : </li></ul><ul><li>Solute concentration of solution equal to that of cell </li></ul><ul><ul><li>No net water movement </li></ul></ul>
  26. 52. application of osmosis Why the use of excess fertilizer caused wilting in plant?
  27. 53. Explain these preservation process

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