1. Ch. 5.3: LIPIDS Objectives:
Identify a general characteristic of lipids.
Describe the structure and function of fats.
Describe the structure and function of steroids.
Vocabulary:
Lipid
Hydrophobic
Fat
Saturated fat
Unsaturated fat
Steroid
Cholesterol

2. 5.3: Lipids FUNCTIONS Store energy Chemical signals to cells
Waxes or oils or fats
HYDROPHOBIC!
Also made of C, H & O, but lower proportion of oxygen
Lipids store more energy than carbohydrates because they have twice as many energy rich (C-H) bonds than carbohydrates.
1 Lipid = 3 fatty acids + 1 glycerol molecule (monomers)
Example: Triglyceride (polymer): Composed of 3 fatty acid molecules joined to 1 Molecule of alcohol glycerol.
FUNCTIONS
Store energy
Chemical signals to cells
Boundary to water in cells (IN CELLMEMBRANE)
Cushion organs

3. A fatty acid is a long hydrocarbon chain with a carboxyl (acid) group at one end.
The Carboxyl End (HEAD) POLAR and HYDROPHILIC.
The Hydrocarbon End (TAIL) NONPOLAR and HYDROPHOBIC.
Saturated fatty acids have no double bonds between their carbon atoms.
Unsaturated fatty acids have double bonds in the carbon chain.

4. 5.3: LIPIDS
Saturated-carbons are joined by all single bonds; room temp.;
Ex: animal fats (bacon fat, etc.), cheeses, butter
not healthy (raise cholesterol)
Unsaturated (mono or poly) –
2 carbons are joined by a double bond
Usu. room temp.
Derived from plants or fish
Ex: olive oil, nuts, fish oils
Healthier fats
Polyunsaturated-carbons have many double bonds

5. Saturated Fats
Unsaturated Fats

6. Saturated Fat Unsaturated Fat

7. 5.3: STEROIDS Steriod - Lipid molecule with 4 fused carbon rings.
Different functional groups attach to rings for different results.
Ex: Testosterone vs. Estrogen (HORMONES); Cortisol, Adrenaline
Act as chemical signals or messengers to cells.
Cholesterol: in cell membranes. Over abundance can clog arteries.

8. 5.3: Phospholipids
PHOSPHOLIPIDS - TWO Fatty Acids joined by a Molecule of Glycerol. 
Called a LIPID BILAYER and forms a barrier between the inside and outside of the Cell.