B1.1.8

• Lipids are macromolecules which contain the chemical elements carbon, hydrogen and oxygen.
• Lipids are only sparingly soluble in water because they are non-polar and so don't attract water molecules - they are hydrophobic.
• Lipids are soluble in organic solvents such as ethanol and acetone.
• 4 types of lipids:

  • Oils
  • Fats
  • Waxes
  • Steroids
• Oils have a melting point below 20°C -> they solidify at low temperatures.
• Fats have a melting point between 20°C and 37°C -> solid at room temperature, liquid at body temperature.
• Waxes have a melting point above 37°C -> they liquify at high temperatures
• Steroids have molecules with a characteristic four-ring structure.