lipids

    Cards (7)

    • lipids
      • macromolecules
      • non-polar
      • all contain C,H and O
      • 3 types triglycerides, phospholipids and cholesterol
    • Triglycerides
      1 glycerol and 3 fatty acids
      synthesised by the formation of ester bonds between each fatty acid molecule
      One triglyceride has three ester bonds (each is formed by a condensation reaction)
      To break down a triglyceride 3 water molecules are needed (hydrolysis)
    • Triglycerides - fatty acids
      long 'tails' made of hydrocarbons (tails are hydrophobic) make lipids insoluble
      two kinds saturated and unsaturated
      saturated - no double bonds between carbons
      unsaturated - have at least one double bond between carbon atoms
      A) saturated
      B) unsaturated
    • Cholesterol
      hydrocarbon ring structure attached to hydrocarbon tail
      hydroxyl group (polar) -> HO -> hydrocarbon rings -> hydrocarbon tail
    • Function of triglycerides
      mainly used as an energy storage molecules (animals & plants)
      some bacteria use to store energy and carbon
      because long hydrocarbon tails contain lots of chemical energy (lots of energy released when broken down)
      insoluble - stops water entering via osmosis
    • Function of phospholipids
      Found in the cell membrane (of all eukaryotes and prokaryotes) - phospholipid
      centre of the bilayer is hydrophobic (hydrophobic tails) so water soluble molecules can't pass through easily
    • Function of cholesterol

      Regulate fluidity of the cell membrane by interacting with the phospholipid bilayer
      small size and flattened shape (allowing it to fit through the phospholipid molecules into the membrane)
      at high temperature bind to hydrophobic tails ->packed close together decreasing fluidity
      at low temperatures prevents packing -> increasing fluidity