Lipids

• Lipids contain carbon, hydrogen and oxygen
• Lipids are insoluble in water and soluble in some solvents like alcohol
• Lipids are made of a glycerol molecule and a few fatty acids
• Role of lipids

  • energy source
  • waterproofing
  • insulation
  • protection
• Triglycerides are composed of one glycerol molecule and three fatty acids
• Saturated fatty acids have single carbon bonds
• Monounsaturated fats have one double bond
• Polyunsaturated fats have more than one double bond
• Unsaturated fatty acids contain double carbon-carbon bonds
• Phospholipids contain glycerol backbone, two fatty acids and a phosphate group
• Phosphate group is hydrophilic and interacts with water
• Fatty acids are hydrophobic and doesn't interact with water
• Lipids contain ester bonds between the glycerol molecule and the fatty acids
• Test for lipids is to add ethanol and shake, then add water and mix
• If lipids are present, white emulsion forms
• Test for lipids is called the Emulsion test