1. Lesson 3
Lipids

2. Lipids Hydrophobic, non-polar
Energy storage, building membranes, chemical signalling
4 main types:
Fats
Phospholipids
Steroids
waxes

3. 1. Fats Energy storage Insulation Cushioning
Carry more energy than carbohydrates
Harder to break down
Insulation
Cushioning

4. Fats 1 +3 = Triglycerides: most common fats in plants and animals
Glycerol backbone + 3 fatty acids
Glycerol is an alcohol
Fatty acids are long hydrocarbon chains (16C – 18C)
Formed with dehydration synthesis 1 +3 =

5. Types of fatty acids Saturated Unsaturated No double bonds
Solid at room temperature
Animal fats, butter, lard
Unsaturated
Have double bonds
Liquid at room temperature
Plant fats

6. Two different unsaturated fats
Cis fat
Hydrogens on same side of double bond
Trans fat
Hydrogens on different sides of double bond
Why is one good and one bad?

7. Fats and health Straight fats are bad Bent fats are good Saturated
Trans unsaturated
Even worse b/c db is hard to break down
Found in fried foods, processed foods, hard margarines
Bent fats are good
Cis unsaturated
Found in vegetables, nuts

8. 2. Phospholipids Make up most of cell membrane
Glycerol + polar phosphate group + 2 fatty acids
Phosphate “head” is hydrophilic
Fatty acid tail is hydrophobic

9. Phospholipids Phospholipid bilayer in cell membrane
Polar and charged molecules cannot pass through

10. 3. Sterols (steroids) Highly hydrophobic
Four rings with varying functional groups attached
Responsible for carrying messages and maintaining fluidity
Ex.
Cholesterol
Sex hormones such as testosterone and estrogen

11. 4. Waxes Hydrophobic solids
Used by animals and plants as waterproofing agents
Ex. Cutin in plants, beeswax, feathers of birds

12. Homework
Describe the general characteristics of lipids and how they are different from carbohydrates.
Compare the chemical energy stored in a gram of fat to the chemical energy stored in a gram of carbohydrate or protein.
What are the functions of fats in living organisms?
What is the most common type of fat found in the body?
Describe its chemical structure.
Draw the condensation reaction that takes place to form a triglyceride.
Draw a diagram of a saturated fatty acid and an unsaturated fatty acid
What are the difference in properties between a triglyceride containing only saturated fatty acids and a triglyceride containing unsaturated fatty acids?
Describe the structure and function of a phospholipid.
Draw a simple diagram of a phospholipid
How do phospholipids play a role in the cell membrane?
Describe the structure of steroids and draw cholesterol.
What is the function of cholesterol?
What are the dangers of a high concentration of cholesterol in the blood stream?
Describe the general function of waxes.