1. AS Biology Core Principles Lipids

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

3. Introduction to lipids

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

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

6. Fatty Acids

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

8. Triglycerides

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

10. Triglycerides

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

12. Phospholipids

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

15. More Info o To make further notes on Lipids : oPages 11 & 12 in Collins oPages 69 - 71 Roberts owww.mrothery.co.ukwww.mrothery.co.uk owww.learn.co.ukwww.learn.co.uk owww.bbc.co.uk/education/asguru/www.bbc.co.uk/education/asguru/