3. dehydration synthesis
Fats
Structure:
fatty acid = long HC “tail” with carboxyl (COOH) group “head”
enzyme
Look at structure… What makes them hydrophobic?
Note functional group = carboxyl
H2O
dehydration synthesis

4. Building Fats Triacylglycerol ester linkage = between OH & COOH
hydroxyl
carboxyl
BIG FAT molecule!!

5. Dehydration synthesis
H2O
dehydration synthesis
enzyme
H2O
Pulling the water out to free up the bond
enzyme
H2O
enzyme
H2O

6. Why do humans like fatty foods?
Fats store energy
Long HC chain
polar or non-polar?
hydrophilic or hydrophobic?
Function:
concentrated
all H-C!
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?

7. Saturated fats long, straight chain most animal fats
solid at room temp.
contributes to cardiovascular disease (atherosclerosis) = plaque deposits
Mostly animal fats

8. Unsaturated fats plant & fish fats vegetable oils
liquid at room temperature
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?

9. Saturated vs. unsaturated

10. It’s just like a penguin…
Phospholipids
Structure:
PO4 = negatively charged (phosphate group)
It’s just like a penguin…
A head at one end
& a tail at the other!

11. Phospholipids Hydrophobic or hydrophilic? fatty acid tails =
PO4 head =
split “personality”
“attracted to water”
Come here, No, go away!
interaction with H2O is complex & very important!
“repelled by water”

12. Phospholipids in water
Hydrophobic tails “hide” from H2O
can self-assemble into “bubbles”
bubble = ______________
can also form a ____________________
early evolutionary stage of cell?
water
bilayer
water

13. Why is this important? define outside vs. inside
they make cell membranes!
Tell them about soap!

14. Steroids Structure: 4 fused C rings + Functional Groups examples:
different steroids created by attaching different functional groups to rings
examples:
cholesterol

15. Cholesterol Important cell component
including vertebrate sex hormones
high levels in blood may contribute to cardiovascular disease

16. Cholesterol

17. From Cholesterol _______________
What a big difference a few atoms can make!
Same C skeleton, different functional groups