• Large and varied group
• Made up of mostly C & H atoms (O too!)
• Do not dissolve in water
• Uses:
– Energy Storage
– Waterproofing
– Structure
– Hormones

• function to cushion organs, as insulation & in long-term energy storage
• Made of two kinds of molecules
– Glycerol
– Fatty acids
• Saturated Fatty Acid:
– Carbons joined by single bonds
– Maximum H atoms
• Unsaturated Fatty Acid:
– At least one double bond between carbons in the fatty acid

Fatty acids that contain 1 or more double bonds between carbon atoms are said to be unsaturated.
Fatty acids with only single covalent bonds between the carbon atoms are referred to as saturated.

Source: http://biology.clc.uc.edu/Courses/bio104/lipids.htm

• Building block of cell membrane
– Only has 2 fatty acids
– 1 phosphate group
• Have
– Hydrophilic heads
– Hydrophobic tails

• Carbon Skeleton has:
– Four interconnected rings
– Different groupings of atoms (or functional groups) attached
• Cholesterol
• Hormones