AP Biology Lipids: Fats & Oils

AP Biology

Lipids energy storage

AP Biology Lipids  Lipids are composed of C, H, O  4 groups:  fats  oils  waxes  steroids  Do not form polymers  big molecules made of smaller subunits  not a continuing chain

AP Biology Lipids Six functions of lipids: 1. Long term energy storage 2. Protection against heat loss (insulation) 3. Protection against physical shock 4. Protection against water loss 5. Chemical messengers (hormones) 6. Major component of membranes (phospholipids)

AP Biology Fats store energy  Function:  energy storage  2x energy of carbohydrates  cushion organs  insulates body  think whale blubber! Why do humans like fatty foods?

AP Biology Fat subunits  Structure:  glycerol (3C alcohol) + fatty acid dehydration synthesis  fatty acid = long “tail” with COOH group at “head”

Fatty Acid Structure Carboxyl group (COOH) forms the acid. “R” group is a hydrocarbon chain (chain of hydrogens and carbons).

A Representative Fatty Acid Hydrocarbon Group Carboxyl Group

AP Biology Saturated fats  All C bonded to H  No C=C double bonds  long, straight chain  most animal fats  solid at room temp.  contributes to cardiovascular disease (atherosclerosis) = plaque deposits

Saturated Fatty Acid Unsaturated Fatty Acid

AP Biology Unsaturated fats  C=C double bonds in the fatty acids  plant & fish fats  vegetable oils  liquid at room temperature  the kinks made by double bonded C prevent the molecules from packing tightly together mono-unsaturated? poly-unsaturated?

AP Biology Saturated vs. unsaturated saturatedunsaturated

AP Biology Waxes Ear wax – protection from foreign materials/ invaders (such as insects) Wax coating on leaves – forms a barrier to keep water in leaves

AP Biology Steroids  Cholesterol  Found in cell membranes – keeps them flexible  Hormones (chemical messengers)

AP Biology Quiz 1. What are the four types of lipids ? 2. Name as many functions of lipids as possible (6). 3. What is the difference in saturated & unsaturated ? 4. How could you tell the difference in saturated & unsaturated by looking at an item ? 5. What is healthier, saturated or unsaturated fats ? 6. Lipids contain more energy than carbs, so why are carbs are primary energy source ? 7. What is the monomer & polymer of lipids ? 8. Structurally, how do you tell the difference in carbs & lipids ?

AP Biology Answers 1. Fats, oils, waxes, & steroids 2. Energy storage, insulation, protection from water loss, protection against physical shocks, chemical messengers, component of cell membranes 3. C=C double bonds are in unsaturated 4. Saturated are solid at room temp., unsaturated are liquid at room temp. 5. unsaturated 6. Lipids are harder to break down, because they are insoluble in water 7. Technically, there are not monomers & polymers 8. Both contain C,H, & O, but in carbs they are in a 1:2:1 ratio