lipids

• what are polymers?

  long chains of repeating units made up from smaller simpler monomers
• what elements do lipids contain?

  carbon, hydrogen and oxygen
• what are two types of lipids and what distinguishes them?

  Fats- solids at room temp

  oils- liquids at room temp
• true or false? lipids are polar

  FALSE- non-polar so they don't dissolve in water
• what is a triglyceride?

  one glycerol and three fatty acids
• what type of compound is a glycerol and a fatty acid?

  • glycerol- alcohol
  • fatty acid- carboxylic acid
  • the functional groups interact forming an ester bond

  
• what is a phospholipid?

  • modified triglyceride
  • one of the fatty acids in a triglyceride is replaced by a phosphate head

  
• why are lipids called surfactants?

  form a layer on the surface of water with the phosphate heads in the water and fatty acid tails sticking out of the water
• what type of molecule is a phospholipid and a triglyceride?

  macromolecule
• were do kinks form in the carbon chain? (C=C bonds)

  in the fatty acid chain
• what is the role of the phospholipid bilayer?

  separated the aqueous environments from aqueous environments within the cytosol
• what kind of molecule is cholesterol?


  a sterol
• true or false? sterols like cholesterol have a dual hydrophobic/philic nature

  TRUE- have a a hydroxyl group which is polar and hydrophilic and the rest of the molecule is hydrophobic
• what is the role of cholesterol in the cell membrane?

  adds stability to the cell membrane- positioned between phospholipids and maintains fluidity- hydrophobic end of cholesterol interacts with hydrophobic end of phospholipid, same for the hydrophilic end. Increases/reduces membrane packing
• state the general roles of lipids within organisms

  • membrane formation and the creation of hydrophobic barriers
  • electrical insulation for nerve impulse transmission
  • hormone production
  • waterproofing
  • thermal insulation to reduce heat loss
  • cushioning to protect vital organs
  • buoyancy for aquatic animals
• how can you test for the presence of a lipid?

  emulsion test- mix sample with ethanol. Resulting mixture is mixed with water and shaken. If a white emulsion forms as a layer on the top solution, this means a lipid is present, if the solution remains clar it's negative