Lipids

• Osmosis- The net movement of water from an area of higher water potential to an area of lower water potential across a partially permeable membrane.
• What elements are lipids made of?

  Carbon, Hydrogen, and Oxygen
• What is the difference between saturated and unsaturated fatty acids?

  • Saturated fatty acids: no C=C double bonds
  • Unsaturated fatty acids: one or more C=C double bonds, causing kinks
• What type of reaction forms ester bonds between glycerol and fatty acids?

  Condensation reaction
• How many ester bonds are formed in one triglyceride molecule?

  Three ester bonds
• What type of lipid contains one glycerol, two fatty acids, and a phosphate group?

  Phospholipid
• True or False: Unsaturated fatty acids have no double bonds in their hydrocarbon tails.

  1. Unsaturated fatty acids do have C=C double bonds
• True or False: Triglycerides are hydrophilic and dissolve easily in water.

  1. Triglycerides are hydrophobic
• True or False: Phosphate groups in phospholipids are hydrophilic.

  1. The phosphate group is hydrophilic
• True or False: Triglycerides affect the water potential of cells.

  1. Triglycerides do not affect water potential
• True or False: Phospholipids form a bilayer in water because of their amphipathic nature.

  1. Phospholipids are amphipathic
• Why do unsaturated fatty acids cause the hydrocarbon tail to "kink"?

  The double bond creates a kink in the tail
• Describe the structure of a triglyceride.

  • One glycerol molecule
  • Three fatty acids
  • Linked by ester bonds through condensation reactions
• Why are triglycerides good energy storage molecules?

  • Hydrocarbon tails store a lot of energy
  • Energy is released during respiration
• Why don’t triglycerides affect the water potential of cells?

  • Triglycerides are insoluble in water
  • They do not cause water movement in cells
• How does the emulsion test for lipids work?

  1. Mix food sample with ethanol and shake
  2. Pour mixture into water
  3. Milky emulsion forms if lipids are present
  4. Solution stays clear if no lipids are present