1. Lipids: Fats & Oils & Wax & Steroid

2. Lipids Lipids are composed of C, H, O 4 groups: Do not form polymers
fats
oils
waxes
steroids
Do not form polymers
big molecules made of smaller subunits
not a continuing chain
Made of same elements as carbohydrates but very different structure/ proportions & therefore very different biological properties

3. 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)
Made of same elements as carbohydrates but very different structure/ proportions & therefore very different biological properties

4. Why do humans like fatty foods?
Fats store energy
Function:
energy storage
2x energy of
carbohydrates
cushion organs
insulates body
think whale blubber!
What happens when you add oil to water
Why is there a lot of energy stored in fats?
• big molecule
• lots of bonds of stored energy
So why are we attracted to eating fat?
Think about our ancestors on the Serengeti Plain & during the Ice Age. Was eating fat an advantage?

5. dehydration synthesis
Fat subunits
Structure:
glycerol (3C alcohol) + fatty acid
fatty acid = long “tail” with COOH group at “head”
Look at structure… What makes them hydrophobic?
Note functional group = carboxyl
dehydration synthesis

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

7. A Representative Fatty Acid
Carboxyl
Group
Hydrocarbon Group

8. Synthesis of a Fat

9. A Phospholipid

10. Hydrophilic vs hydrophobic
Hydrophilic – Water loving – soluble in water
Hydrophobic – water hating – is NOT
soluble in water
Triglyceride =1 glycerol, 3 fatty acids
Hydrophilic
Phospholipids = 1 glycerol,
2 fatty acids 1 phosphate group
tails are hydrophobic
the heads are hydrophilic.
make up cell membranes

11. 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
Mostly animal fats

12. Unsaturated
Fatty Acid
Saturated
Fatty Acid

13. 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
Mostly plant lipids
Think about “natural” peanut butter:
Lots of unsaturated fats Oil separates out
Companies want to make their product easier to use:
Stop the oil from separating Keep oil solid at room temp.
Hydrogenate it = chemically alter to saturate it
Affect nutrition?
mono-unsaturated?
poly-unsaturated?

14. Saturated vs. unsaturated

15. If fatty acids are unsaturated, their shape is altered from a saturated molecule so the molecules in the Lipid push apart, thus making it more fluid and oily.
Animals tend to have more saturated, and consequently solid at room temperature lipids whereas plants tend to have more unsaturated and so fluid at room temperature lipids

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

17. Steroids Cholesterol Hormones (chemical messengers)
Found in cell membranes – keeps them flexible
Hormones (chemical messengers)

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

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