EKQu's| Biological Molecules Lipids

What are the components of a triglyceride?

Glycerol and 3 fatty acids

Name the reaction when these components join together.

Name the bonds formed during this reaction. How many water molecules are formed?

condensation reaction → ester bonds → three

Describe how you would test a liquid sample for the presence of lipid and how you would recognise a positive result.

1. .(Mix / shake sample) with ethanol, then water;

   Sequence is important

   2.    White / milky (emulsion);

Mucus produced by epithelial cells in the human gas exchange system contains triglycerides and phospholipids.

Compare and contrast the structure and properties of triglycerides and phospholipids.(5)

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

and hydrophobic region;

Accept 'non-polar' for hydrophobic and 'polar' for hydrophilic.

8. Phospholipids form monolayer (on surface)/micelle/bilayer (in water) but

triglycerides don't;

Describe how a saturated fatty acid is different from an unsaturated fatty acid

Saturated single/no double bonds (between carbons)

OR

Unsaturated has (at least one) double bond (between carbons);