Lipids are composed of: • Carbon • Hydrogen • Oxygen “CHO” BUT: Lipid molecules have a larger number of Carbon and Hydrogen and a smaller number of Oxygen than Carbohydrates

Properties of Lipids • Fats, oils, and waxes are lipids.

• Unlike the other organic compounds, lipids do not dissolve in water; therefore, they are nonpolar or insoluble.

Lipid Functions • Lipid molecules provide a barrier b/t a cell and its watery environment

Lipid Functions • Insulation of whales and walruses

Lipid Functions • Skin oils help repel water from feathers of ducks

Lipid Functions • Waxy layer of plants, keeps water in

Fatty Acids • Lipids are composed of building blocks or MONOMERS called Fatty Acids.

Fatty Acids • Carboxyl end (-COOH) – polar – Hydrophilic: “water loving” – Hydrocarbon end (CH 3 ) • Non-polar • Hydrophobic: “Water fearing”


Arrangement of FA in Cell

Functions of Lipids • Store Energy!!

• Fats have more H bonds than Carbs and can store more energy.

Kinds of LIPIDS 1. Triglycerides 2. Waxes 3. Steriods 4. phospholipds

Triglycerides Composed of: 1. 1 glycerol molecule 2. 3 molecules of fatty acids

TWO categories of triglycerides 1. Saturated 2. unsaturated

• Plant waxes – Forms protective coating on outer surface Waxes • Earwax – Prevents bacteria from entering middle ear


• Composed of 4 carbon rings • Found : – Hormones – Toad venom – Plant poisons – Chlorophyll – Cholesterol