1. LIPIDS Diverse group of organics Insoluble in water
Will dissolve in nonpolar solvents
MAJOR GROUPS
FATS
PHOSPHOLIPIDS
STEROIDS

2. Fats Store Large Amounts of Energy
COMPONENTS of a FAT:
GLYCEROL: A 3-Carbon Alcohol
FATTY ACID (Carboxylic Acid)
*Carboxyl at one end attached to a hydrocarbon chain
*Carboxyl end has acid properties
*Usually contains a long C skeleton with an
even number (Most have 16-18C’s)
*Nonpolar C-H bonds make the chain
hydrophobic

3. LIPID FORMATION
Enzyme catalyzed condensation reactions link glycerol to fatty acids by an Ester Linkage:
ESTER LINKAGE: Bond formed between a hydroxyl group and a carboxyl group
TRIACYLGLYCEROL (Triglyceride)
A fat composed of three fatty acids bonded to a glycerol by ester linkages

4. The Making of a Triglyceride

5. ! Insoluble in water Variation is due to fatty acid composition
Fat Characteristics
Insoluble in water
Variation is due to fatty acid composition
Fatty acids can be the same or different, including different lengths, and have C=C double bonds in different places

6. Saturated and Unsaturated Fats
No double bonds between C’s in fatty acid tail
C’s bonded to max # of H’s (saturated w/H)
Usually solid at room temp.
Most animal fats
UNSATURATED FATS:
One or more double bonds between C’s in fatty acid tail
Tail kinks at each C=C, so molecules are spread out more
Usually liquid at room temp.
Most plant fats

7. FAT FUNCTIONS
Energy Storage: 1 Gram of fat=2X energy of 1 Gram of Polysaccharide!!!
More compact energy storage
Cushions mammal’s organs
Insulates against heat loss

8. PHOSPHOLIPIDS
Glycerol, 2 fatty acids, a phosphate group, and usually a small chemical group attached to the phosphate.(Campbell 5.12)
Phosphate is negatively charged
Variable group is usually charged or polar
Can be diverse
Aren’t truly hydrophobic or hydrophilic (Hydrocarbon tails are hydrophobic, polar head is hydrophilic)
Are major components of cell membranes: Form a bilayer due to reaction of hydrophobic tails
A MICELLE or phospholipid cluster forms spontaneously in water

9. STEROIDS
Lipids which have 4 fused carbon rings with various functional groups attached
Cholesterol is an important steroid:
Precursor to many other steroids including sex hormones and bile acids
Common component of animal cell membranes
Can contribute to artherosclerosis

10. CHOLESTEROL