Lipids

Lipids

1. Triglycerides

   • Structure
     • Macromolecules
     • Carbon, Hydrogen, Oxygen
     • 1 molecule of Glycerol and 3 Fatty Acid chains attached
     • They have long, fatty acid, hydrocarbon 'tails'
       • Tails are hydrophobic
         • Lipids are insoluble
       • Hydrocarbon tail varies
   • Ester Bond
     • Ester bonds form between the glycerol and fatty acid by a condensation reaction
       • Esterification
     • Hydrolysis reactions can break the bonds
   • Fatty Acids
     • Saturated
       • No double bonds between Carbon atoms
     • Unsaturated
       • At least one double bond causes kink

2. Phospholipids

   • Macromolecules
   • Similar structure to triglycerides but have a phosphate group instead of a fatty acid
   • Phosphate group is hydrophilic and tail is hydrophobic

3. Functions

   • Triglycerides
     • Hydrocarbon tails contain loads of chemical energy, which is released when they are broken down
     • Good energy storage molecules for animals and plants
     • They are insoluble because of the hydrophobic tail and the formation of insoluble droplets. Prevents water entering
   • Phospholipid
     • Make up the phospholipid bilayer in cell membranes
       • Acts as a barrier to water-soluble substances
     • Double layer of hydrophilic heads facing out and hydrophobic heads facing in
   • Cholestrol
     • Small and flattened shape
       • Fit in between phospholipid molecules
     • Bind to hydrophobic tails and pack more closely
       • Less fluid and more rigid

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