Biological Molecules- Lipids

  • Created by: gsemma
  • Created on: 09-01-19 10:26
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  • Lipids
    • a group of substances containing large amounts of carbon and hydrogen
      • insoluble in water but are soluble in alcohol because they are non-polar
    • glycerol molecule
      • glyceride (draw)
        • 3 fatty acids (draw)
          • Triglycerides (draw)
            • lipids made of one glycerol molecule and 3 fatty acids joined by an ester bond
            • functions
              • energy source- respired to rlase ATP
                • insoluble in water and high prop. of hydrogen means more energy is released per gram of fat then a gram of glucose
              • insulation- the adipose tissues store fats in animals to keep them warm
              • buoyancy- less dense than water so helps floating
              • protection- forms a layer of mechanical insulation around vital organs
          • saturated- no C=C bonds. max amount of H
            • Unsaturated- C=C bonds
              • 1 C=C- mono-unsaturted
                • more than 1= poly-unsaturated
              • kinked due to double bond- take up more space hence lower melting points
      • each hydroxyl group can be lost to form an ester bond with a fatty acid
    • ester bond
      • draw below
      • each glycerol molecule can form covalent ester bonds with 3 fatty acids
        • condensation reaction
          • the water molecule released is dervived from the OH groups from the fatty acid and glycerol
    • phospholipids
      • a glycerol molecule bonded to 2 fatty acids and 1 phosphate group
        • found in cell membranes in phospholipid bilayers
        • phosphate head is hydrophilic so dissolves on outside of bilayer
        • fatty tail is hydrophobic so form a barrier that water-soluble molecules cannot pass
    • Test
      • Emulsion test
        • shake sample with ethanol- if turns milky white- lipid present

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