lipids

Cards (15)

  • Biochemical test for lipids
    1) Crush sample
    2) Add ethanol and shake
    3) Then add water
    4) A white emulsion forms of lipids are present
  • What are the two groups of lipids?
    Triglycerides Phospholipids
  • What are the roles of lipids in the body?
    Phospholipids = Important component of cell membranes
    Triglycerides = Energy storage, found in food
  • How are triglycerides formed?
    Condensation of one molecule of glycerol and three fatty acid molecules

    NOT A POLYMER AS IT ISN'T MADE OF THE SAME MONOMERS
  • How is an ester bond formed?

    A condensation reaction between glycerol and a fatty acid (RCOOH)
  • What elements do all lipids contain?
    Carbon
    Hydrogen
    Oxygen
  • What are fatty acids?
    Consist of a hydrocarbon chain and a carboxylic acid group.
    The hydrocarbon chains vary in length and can be referred to as 'R' (whole fatty acid = RCOOH)
  • What is the 'R' group?

    Variable hydrocarbon chain
  • What is a saturated fatty acid?

    Single bond between carbon atoms in the hydrocarbon chain
  • What is an unsaturated fatty acid?

    Double bond between the carbon atoms in the hydrocarbon chain
  • Describe the difference between the structure of a triglyceride and a phospholipid
    A triglyceride has 3 fatty acids attached to the glycerol whereas in a phospholipid one fatty acid is replaced by a phosphate
  • What do triglycerides do in water?
    Clump together
    Fatty acid tails face onwards to shield themselves from water with their glycerol heads
    Forming insoluble droplets
  • Triglycerides - structure
    The fatty acid tails are hydrophobic (repel water) making them insoluble in water
  • Phospholipids - structure
    Phosphate group has a negative charge (polar) whereas the fatty acid tails don't have a charge (non polar)

    Phosphate head = hydrophilic (attracts water) - water soluble
    Fatty acid tails = hydrophobic (repel water)

    Allowing them to form a bilayer in water
  • Describe and explain how phospholipids are arranged in a cell membrane
    - Phospholipids are arranged in a bilayer
    - The phosphate heads face the outside and inside of the cell so that they are in contact with water because they are hydrophilic
    - The fatty acid tails are in the middle of the membrane away from the water because they are hydrophobic