Lipids

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  • lipids
    • function
      • energy source- can be respired to release energy to generate ATP
      • energy storage - more energy is yielded per gram than carbs, found in "fat stores" in adipose cells
      • insulation - e.g electrical insulations around long nerve cells and below the skin, blubber in whales
      • protection against knocks
    • groups
      • triglycerides
        • most common form of lipids
        • solid at room temp = fats, liquid at room temp = oils
        • made up of  one glycerol molecule and 3 fatty acids
          • glycerol = the head (hydrophilic) and the fatty acids = the tail (hydrophobic)
          • the glycerol and fatty acid are joined together by an ester bond during a condensation reaction
      • phospholipids
        • phosphate = the head (hydrophilic) and 2 fatty acids plus a glycerol = the tail
        • creates the phospholipid bilayer, found in the fluid mosaic model (cell membrane)
      • cholesterol
      • steroid hormones
    • saturated fats
      • solid at room temperature (fat)
      • has C-C bonds
      • max. number of H-bonds/atoms
      • animal fat
      • less healthy because they are solid, linked to diets that are poor
      • high melting point
    • unsaturated fats
      • have C=C bonds
      • often oils
      • fewer H-atoms are bonded to the molecule
      • plants
      • don't  contain max. number of hydrogen atoms
      • 1 C=C bond = monounsaturated, 2 or more C=C bonds = polyunsaturated
        • more = healthier because increases the fluidity of the molecule
      • lower melting point
    • ethanol emulsion test: mix the sample with ethanol (this will dissolve any lipids), pour the solution into water in a new test, if lipids are present there will be a cloudy white emulsion at the top, the lips comes out of the solution and becomes dispersed as tiny droplets in the water.

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