1. Lipids (fats and oils) The formation of a triglyceride one molecule + three moleculesone molecule +water of glycerolof fatty acidsof a triglyceride H H H C OH + HOOC.R 1 H C OOC.R 1 H C OH + HOOC.R 2 H C OOCR 2 + 3H 2 O H C OH + HOOC.R 3 H C OOC.R 3 H H

2. Ester link The reactions between the fatty acids and glycerol are examples of condensation reactions i.e. water is eliminated. The glyceride molecule is always the same but the fatty acids vary. The condensation reaction occurs between the carboxyl group (COOH) of the fatty acid and the hydroxyl group (OH) of the glycerol. H O H O H C OH HO C R H C O C R ester link

3. Phospholipids Phospholipids are important componants of the cell membrane. One of the glycerol hydroxyl groups is esterified by phoshoric acid (H 3 PO 4 ) rather than by a fatty acid ester links ( O ) H H H C OH + HOOC.R 1 H C OOC.R 1 H C OH + HOOC.R 2 H C OOCR 2 + 3H 2 O H C OH + HO P OH H C OP O(H) H OH O H OH O

4. Simplified structure fatty acids - non-polar glycerol hydrophobic (repels water) phosphate group - polar hydrophilic (attracts water)