3.1.2: Lipids

Question 1

How are triglycerides formed

Answer 1

1. One glycerol and three fatty acids;
2. Condensation(reactions) and removal
   of three molecules of water;
3. Ester bond(s) (formed);

Question 2

compare phospholipids with Triglycerides (8)

Answer 2

1. Both contain ester bonds (between glycerol
   and fatty acid);
2. Both contain glycerol;
3. Fatty acids on both may be saturated or
   unsaturated;
4. Both are insoluble in water;
5. Both contain C, H and O but phospholipids also
   contain P;
6. Triglyceride has three fatty acids and
   phospholipid has two fatty acids plus phosphate
   group;
7. Triglycerides are hydrophobic/non-polar and
   phospholipids have hydrophilic/polar and
   hydrophobic/polar
   region;
8. Phospholipids form monolayer (on
   surface)/micelle/bilayer (in water) but
   triglycerides don’t;

Question 3

Describe how an ester bond is formed in a
phospholipid molecule.

Answer 3

1. Condensation reaction
2. Between glycerol and fatty acid

Question 4

Describe the test for lipids

Answer 4

1. (Mix / shake sample) with ethanol,
   then water;
   Sequence is important
2. White / milky (emulsion);