1.  Lipids: a large and varied group of organic compounds.
 Lipids include:
Triglycerides
Phospholipids
Waxes
Cholesterol and Steroids
 Lipids are all non-polar and do not dissolve in water

2.  Triglycerides are one of the most common types of lipids
 Triglycerides consist of one molecule of glycerol bonded to three fatty acid molecules
 Each fatty acid is linked to the glycerol molecule by an ester bond C H OH
Glycerol
Hydroxyl groups

3. Carboxyl group
Fatty Acids:
General Formula:
CH3
(CH2)n C O OH
CH3 H C O OH
CH2

4. H C O OH
Can be drawn as: C O OH

5. This is a condensation reaction
Forming a monoglyceride: C O OH C H OH
Hydroxyl group and carboxyl group react
Ester bond C H OH O
+ H2O
This is a condensation reaction

6. A triglyceride: C H O
Glycerol
Fatty acid
Can be drawn as:
Ester bond

7. This is a hydrolysis reaction
To split these ester bonds and separate a fatty acid from glycerol we need to add a molecule of water C H OH O C H OH
+ H2O C O OH
This is a hydrolysis reaction

8. Uses of Lipids in Living Things
1. Long-term energy stores
Human Adipose Tissue
Plant Oils

9. 2. Buoyancy for marine. animals: lipids are less. dense than water so
2. Buoyancy for marine animals: lipids are less dense than water so help animals float
3. Insulation: a layer of fat beneath the skin cuts down heat loss

10. Camels’ humps are made of fat
4. Production of water: fatty acids produce a lot of metabolic water when they are oxidised during respiration
e.g. C17H35COOH + 26 O2  18 CO H2O
(a typical fatty acid)
Camels’ humps are made of fat

11. Homework:
Compare the relative advantages and disadvantages to an organism of using carbohydrates and lipids as energy stores
To be handed in on a separate sheet of paper.