1. Lipids
AP Biology

2. Lipids

3. Lipids Lipids are composed of C, H, O Major Types of Lipids
_______________________ (H-C)
Major Types of Lipids
______ and ______
______________
___________
__________
Made of same elements as carbohydrates but very different structure/ proportions & therefore very different biological properties

4. Functions of Lipids ________________ ______________ body organs
Think ________
_______________
Think duck feathers
Cell-to-cell communication
Think _________
Formation of cell ________________

5. Basic Structure of Lipids
Do _____ form “polymers” exactly
Not big molecules made of smaller subunits
not a “choo-choo train” of monomers
Mostly long chains of carbon and hydrogen atoms stuck to a “hook”….
_______ =
the hook

6. dehydration synthesis
Fats and oils
Structure:
____________ (3C alcohol) + _____________
fatty acid = ___________ _____ “tail” with carboxyl (COOH) group “head”
enzyme
Look at structure… What makes them hydrophobic?
Note functional group = carboxyl
H2O
dehydration synthesis

7. Building Fats _________________ ____ fatty acids linked to glycerol
________ linkage = between OH & COOH
hydroxyl
carboxyl
Yet
Another
type of
________
bond
BIG FAT molecule!!

8. Dehydration synthesis
H2O
___________ synthesis
enzyme
H2O
Pulling the water out to free up the bond
enzyme
H2O
enzyme
H2O

9. Why do humans like fatty foods? very evenly – no polarity
Fats store energy
Long HC chain
polar or non-polar?
hydrophilic or hydrophobic?
Function:
energy ____________
concentrated
all ______ Bonds
___x energy of
carbohydrates
C and H share electrons
very evenly – no polarity
results.
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?

10. Why is Fat the preferred energy storage molecule of animals
Why is Fat the preferred energy storage molecule of animals? (as opposed to starch)
More ________ Bonds than in carbs…Remember the Glucose molecule:

11. C O C C C C 5' 4' 1' 3' 2' CH2OH 6' H OH H OH H H OH H OH Where’s the
energy?
CH2OH 6' C O
In the C-H BONDS!! 5' H OH H C C 4' 1' OH H H OH C C 3' 2' H OH

12. In lipids there are even MORE C-H bonds than in carbs!
Thus, ________ energy packed in a lipid per unit mass
_______ as much as in a carbohydrate!
ALL ________!!!

13. Saturated vs. Unsaturated Fats
Remember that covalent bonds can be
Single, double, or triple
In Fatty acids, generally the covalent bonds between the carbons are _____________
However, sometimes a ____________ bond can exist between carbons
A DOUBLE bond can cause __________ in the carbon chain.

14. Saturated fats
This means that all the carbons are _______________ with __________________!
This means each carbon is holding as many hydrogens as it possibly can (__ H’s per C)
___ C=C double bonds
This results in long, ______________ chains
These can pack ___________together
______at room temp.
_____________ fats, typically
Butter, lard
Mostly animal fats

15. Unsaturated fats C=C double bonds in the fatty acids
Called ___saturated because the carbons are ____ holding hands with as many hydrogens as possible
C=C double bonds cause the fatty acid to ________
______ at room temperature
the kinks made by double bonded C ____________the molecules from packing tightly together
plant & fish fats
vegetable ________
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?

16. Saturated vs. unsaturated
___________
__________

17. It’s just like a penguin…
________
Phospholipids
Often drawn
Like this
Structure:
glycerol + ___ fatty acids + ______
PO4 = _________ group
PO4 = ___________ charged
__________
It’s just like a penguin…
A head at one end
& a tail at the other!

18. 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”

19. Phospholipids in water
Hydrophilic heads “_________” to H2O
Hydrophobic tails “_______” from H2O
can ______-assemble into “bubbles”
bubble = “micelle”
can also form a ______________________
“bubbles” of phospholipids an early evolutionary step for cells?
water
bilayer
water

20. Phospholipids & cells Phospholipids of cell membrane
double layer = _____layer
hydrophilic heads on _____________
in contact with aqueous solution outside of cell and inside of cell
hydrophobic tails on ______________
form _______
Phospholipid bilayer
Note other molecules in membrane…

21. Why is this important? Phospholipids create a __________ in water
define outside vs. inside
they make ______________________!
Tell them about soap!

22. Steroids Structure: ____ fused C ___________ + ??
different steroids created by attaching different _________________________ to rings
different _____________creates different _________________
examples: ___________________________
cholesterol

23. Cholesterol Important cell component animal cell ____________________
____________ of ____ other steroids
including vertebrate ______ hormones
high levels in blood may contribute to cardiovascular disease

24. Cholesterol Important component of cell membrane
helps keep cell membranes _________ yet ________

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

26. Any Questions?