unit 1 lipids

Question 1

How are triglycerides formed (3)

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

Phospholipids compared 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 bilayer (in water) but triglycerides don’t;

Question 3

Describe how an ester bond is formed in a

phospholipid molecule. (2)

Answer 3

1. Condensation reaction
2. Between glycerol and fatty acid

Question 4

Test for a lipid

Answer 4

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