Lipids, membranes and cholera

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  • Created by: emma
  • Created on: 19-03-14 16:00
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  • Lipids, membrane + cholera
    • Structure
      • Triglycerides
        • 3 fatty acids joined to 1 glycerol
      • Phospholipids
        • 1 phosphate and 2 fatty acids attached to 1 glycerol
      • Staturated
        • No double c-c bonds in hydrocarbon chain
      • Unsaturated
        • Has double c-c bonds in hydrocarbon chain
    • Emulsion test
      • Add 2cm3 of ethanol to sample
        • Shake mixture so fat dissolves
          • Add water and shake again
            • White cloudy emulsion of fat droplets form
    • Diffusion
      • Net movement of molecules from an area of high concentration to low concentration
      • Temperature, Surface area, Concentration gradient
      • Facillitated diffusion
        • Hydrophilic substances cant pass through hydrophobic phospholipid bilayer
          • Moves through a channel protein or carrier protien
    • Osmosis
      • Movement of water from a high water potential to low water potential across a partially permeable membrane
      • Water  potential
        • Pressure created when free water molecules collide with membrane
          • more free water molecules more pressure so greater water potential
      • Hypotonic
        • Cell swells, high wp outside, low wp inside
      • Hypertonic
        • Cell shrivels, High wp inside, low wp outside
    • Active transport
      • Against concentration gradient
      • Requires ATP and carrier protein
    • Co transport
      • Na and Glucose are co transported across membrane via facilitated diffusion
        • At other side of cell Na is actively transported into blood
          • maintaining low conc of Na in cell
          • Glucose enters blood via facilitated diffusion from high to low concentration
    • Cholera
      • Releases toxin in small intestine
        • Causes increases in active transport of ions into lumen
          • Lowers water potential in lumen
            • Water moves from cells into lumen via osmosis
              • Causes diarrhoea
      • Oral re-hydration solution
        • Contains Na and glucose
          • Co transported into cells of small intestine
            • Lowers water potential in cell
              • Water moves from lumen into cell via osmosis
    • Lactose intolerance
      • No lactase enzyme so Lactose cannot be broken down
        • It cannot be absorbed by small intestine
          • Lactose remains in lumen which lowers water potential
            • Water moves from cells into lumen via osmosis
  • Joined by ester bond to glycerol and condensation reaction
    • 1 phosphate and 2 fatty acids attached to 1 glycerol
    • 3 fatty acids joined to 1 glycerol

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