Lipids

• What are lipids primarily made from?

  Triglycerides
• What characterizes saturated fatty acids?

  They have no double bonds between carbon atoms
• What is the effect of double bonds in unsaturated fatty acids?

  They cause the chain to kink
• What is released during the formation of triglycerides?

  A molecule of water
• How are triglycerides formed?

  Through condensation reactions of glycerol and fatty acids
• What is the main difference between triglycerides and phospholipids?

  Phospholipids have a phosphate group
• What is the hydrophilic part of a phospholipid?

  The phosphate group
• Why are triglycerides good for energy storage?

  They contain lots of chemical energy
• How much energy do lipids contain compared to carbohydrates?

  About twice as much energy per gram
• Why are triglycerides insoluble in water?

  They have hydrophobic fatty acid tails
• What happens to triglycerides in cells?

  They form insoluble droplets
• What is the emulsion test used for?

  Testing for the presence of lipids
• What is the first step in the emulsion test?

  Shake the test substance with ethanol
• What indicates a positive result in the emulsion test?

  A milky emulsion forms
• What are the components of a triglyceride?

  Glycerol and three fatty acids
• What distinguishes saturated from unsaturated fatty acids?

  Saturated have single bonds; unsaturated have double bonds
• What is the structure of a phospholipid?

  One phosphate group and two fatty acids
• Why do phospholipids form bilayers in cell membranes?

  Hydrophilic heads face water; hydrophobic tails face inward
• What do amino acids contain?

  An amine group and a carboxyl group
• What links amino acids together?

  Peptide bonds
• What are the properties of triglycerides and phospholipids related to their structures?

  • Triglycerides:
  • Energy storage molecules
  • Long hydrocarbon tails provide energy
  • Insoluble in water
  • Phospholipids:
  • Form cell membranes
  • Hydrophilic heads and hydrophobic tails
• What is the process of triglyceride formation?

  1. Glycerol and fatty acids undergo condensation reactions
  2. Water is released
  3. Three fatty acids attach to glycerol
• What are the uses of lipids in biological systems?

  • Energy storage
  • Structural components of cell membranes
  • Hormones (e.g., testosterone)
  • Respiratory substrates in energy release
• What is the emulsion test procedure for lipids?

  1. Shake sample with ethanol
  2. Add equal volumes of water
  3. Observe for a milky emulsion
• What are the differences between saturated and unsaturated fatty acids?

  • Saturated:
  • No double bonds
  • Straight chains
  • Unsaturated:
  • One or more double bonds
  • Kinked chains
• What are the components of amino acids?

  • Amine group (-NH₂)
  • Carboxyl group (-COOH)
  • Side group (R group)
• How do amino acids link to form proteins?

  • Amino acids form peptide bonds
  • Create polypeptides during protein synthesis