1. AS Biology Core Principles
Lipids

2. Aims Elements of lipids Structure of glycerol & fatty acids
Condensation reactions to form triglycerides
Phospholipids

3. Introduction to lipids

4. Introduction to lipids
Lipids contain the elements carbon, hydrogen and oxygen.
They have numerous functions, primarily energy stores in animals and plants.
Lipids consist of two types of molecules - glycerol & fatty acids.

5. Glycerol A molecule of glycerol is made up of three carbon atoms.
Each of these has a hydroxyl group attached to it.
Hydrogen atoms occupy the remaining positions.

6. Fatty Acids

7. Fatty Acids
A single fatty acid molecule contains an acid (COOH) group attached to a hydrocarbon chain.
Hydrocarbon usually denoted by the letter ’R’.
Saturated = If every carbon atom in the chain is joined by a single C-C bond.
Unsaturated = at least one C=C bond.
Polyunsaturated = many double bonds.
Most animal fats are saturated while most plant fats are unsaturated.

8. Triglycerides

9. Triglycerides
A triglyceride molecule is made of a glycerol molecule and three fatty acids.
The molecules join together through the process of condensation losing a molecule of water each time a link is made.
The link between the glycerol molecule & each fatty acid is an ‘Ester Link’.
The fatty acids in a lipid molecule can differ in length and can be saturated or unsaturated.

10. Triglycerides

11. Phospholipids
In phospholipids one of the fatty acids of a triglyceride is substituted by a phosphate group.

12. Phospholipids

13. Phospholipids

14. Lipids & water
Triglycerides and phospholipids have hydrophobic and hydrophilic groups.
What does this mean?
To what use is this feature put in biology?

15. More Info To make further notes on Lipids : Pages 11 & 12 in Collins
Pages Roberts

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