3.1.3 Lipids

• Lipids- fat-soluble, naturally occurring molecule which are insoluble in water
• Examples of lipids:

  • Fats
  • Oils
  • Waxes
  • Cholesterol
  • Phospholipids
• Properties of lipids:

  • insoluble in water
  • used as a fuel
  • highly concentrated energy store
  • act as recognition molecules
  • component of membranes
• Triglyceride- a molecule made up of one glycerol attached to three fatty acids by three ester bonds, large store of high energy
• Double bond- two bonds between carbon atoms in a hydrocarbon, causes bending, can be multiple carbon to carbon double bonds
• Single bond- one bond between carbon atoms in a hydrocarbon which is straight
• Testing for lipids:

  • Add ethanol to sample
  • Add distilled water, shake test tube
  • Positive test= white emulsion
• Carboxyl group- -COOH

  A) hydroxyl

  B) oxygen

  C) carbon

  D) carboxyl

  
• Structure of a triglyceride:

  A) glycerol

  B) fatty

  C) fatty

  D) esterbond

  E) fatty

  
• Structure of a phospholipid:

  A) phosphate

  B) hydrophilic

  C) glycerol

  D) fatty

  E) fatty

  F) hydrophobic

  G) ester

  
• Phospholipid vs Triglyceride:

  A) phospholipid

  B) triglyceride

  C) phobic

  D) philic

  E) phobic

  F) right

  G) three

  H) one

  I) left

  J) two

  K) right

  L) phosphate

  M) acids

  N) acids

  O) three

  P) two

  Q) no

  R) two

  S) three

  
• Uses of phospholipids:

  • Forms the phospholipid bilayer
  • Forms a hydrophobic bilayer between inside and outside of the cell
  • Controls fluidity in the membrane
• Membrane stabilised:

  A) bent

  B) straight

  C) cholesterol

  D) unsaturated

  E) saturated

  
• Carbohydrates can combine with phospholipids to form glycolipids, which are important for cell recognition.

  A) carbohydrate