1. The formation of a triglyceride
Lipids (fats and oils)
The formation of a triglyceride
one molecule three molecules one molecule + water
of glycerol of fatty acids of a triglyceride
H H
H C OH HOOC.R1 H C OOC.R1
H C OH HOOC.R H C OOCR H2O
H C OH HOOC.R H C OOC.R3
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 (H3PO4) rather than by a fatty acid
ester links ( O )
H H
H C OH HOOC.R1 H C OOC.R1
H C OH HOOC.R H C OOCR H2O
H C OH HO P OH H C OP O(H)
H OH O H OH O

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