1. The Chemistry of Life Lipids
Ms. Richardson - SBI4U

2. Lipids Hydrophobic molecules (“water fearing”).
They are generally nonpolar and are insoluble in water
Includes fats, phospholipids, steroids and waxes
A gram of fat stores 9 calories of energy (compared to 4 calories in carbohydrates and proteins)
Used for energy storage, cushioning, and insulation
Animals convert excess carbohydrates into fat and store the fat as droplets in the cells of adipose (fat) tissue

3. Fats Fats (e.g. trigylcerides)
The backbone is GLYCEROL which has 3 hydroxyls
Each FATTY ACID has a terminal carboxylic acid,between 16 and 18 carbons
Condensation reaction attaches 3 fatty acids to glycerol making ester linkages (esterification)

4. Saturated Fats Usually come from animals.
Used for long-term energy storage, insulation, protection and helps dissolve fat soluble vitamins.
NO double bonds between carbon atoms in the fatty acids
Solid at room temperature due to the straight chains 
fatty acids are closer together
more intermolecular forces

5. Unsaturated Fats Usually comes from plant oils.
One or more double bonds between carbon atoms in fatty acids.
Double bonds form kinks, producing more space between fatty acids thus reducing the number of intermolecular interactions
Liquid at room temperature.

6. Phospholipids
Composed of one glycerol, two fatty acids and a highly polar phosphate group.
Form cellular membranes (phospholipid bilayer).
The phospholipid bilayer is virtually impermeable to macromolecules, relatively impermeable to charged ions, and quite permeable to small, lipid soluble molecules.
O2 and CO2 diffuse through with very little resistance.
Larger molecules pass through the membrane using carrier proteins (facilitated diffusion).

7. Phospholipids

8. Steroids Hydrophobic molecules
Four fused hydrocarbon rings with several functional groups attached
Cholesterol is converted, by the body, into bile salts and vitamin D
Other steroids include sex hormone (e.g. estrogen, testosterone, progesterone)

9. Waxes E.g. bees wax, paraffin, cutin
Consists of ALCOHOL or CARBON RINGS with an ester linkage to a FATTY ACID
They are hydrophobic
Act as waterproof coatings on various plant and animal parts