Lipids

• Lipids


  Biomolecules that contain hydrocarbons and make up the building blocks of the structure and function of living cells
• Lipids


  • They are largely nonpolar in nature because they are hydrocarbons that include mostly nonpolar carbon to carbon or carbon-hydrogen bonds
  • Nonpolar molecules are hydrophobic or water fearing or insoluble in water
• Major types of lipids

  • Fats and oils
  • Waxes
  • Phospholipids
  • Steroids
• Fat molecule


  Consists of two main components: glycerol and fatty acids
• Glycerol


  An organic compound with three carbons, 5 hydrogens, and 3 hydroxyl groups
• Fatty acids


  Have a long chain of hydrocarbons to which a carboxyl group is attached
• The number of carbons in the fatty acid may range from 4 to 36, with most common being 12 to 18 carbons
• Triglycerides


  Formed by the joining of three fatty acids to a glycerol backbone in a dehydration reaction, releasing three molecules of water
• Saturated fatty acid


  Fatty acid chain with only single bonds between neighboring carbons
• Unsaturated fatty acid


  Fatty acid chain containing one or more double bonds
• Examples of unsaturated fats

  • Monounsaturated fats (e.g. olive oil, peanut oil, canola oil)
  • Polyunsaturated fats (e.g. sunflower oil, corn oil, soybean oil, flaxseed oil)
• Waxes


  Made up of long fatty acid chains esterified to long chain alcohols, have hydrophobic nature to prevent water from sticking to surfaces
• Phospholipids


  Molecules with two fatty acids and a modified phosphate group attached to a glycerol backbone, are amphiphatic with hydrophobic and hydrophilic parts
• Steroids


  Have a fused ring structure, often with a short tail and a hydroxyl functional group, are hydrophobic and insoluble in water
• Cholesterol


  The most common steroid, synthesized mainly in the liver, is a precursor to steroid hormones, vitamin D, and bile salts, is a component of the plasma membrane
• Lipids perform many functions: store energy, provide insulation, are building blocks of hormones, are important for all cellular activities