AP Biology
Lipids: Fats & Oils
AP Biology
Lipids
long term energy storage
concentrated energy
AP Biology
Lipids
Lipids are composed of C, H, O
long hydrocarbon chains (H-C)
Ex. C57H110O6 (lard)
“Family groups”
Fats, oils, waxes
phospholipids
steroids
Do not form polymers
AP Biology
Fats
Structure:
glycerol (3C alcohol) + fatty acid
fatty acid =long HC “tail” with carboxyl (COOH) group“head”
Ex. C15H31COOH, C17H35COOH
AP Biology
Saturated vs. Unsaturated Fatty Acids
Saturated
Ex. C17H35COOH
Unsaturated
C17H33COOH
Mono-unsaturated
Polyunsaturated
AP Biology
Building Fats
Triacylglycerol (triglyceride)
3 fatty acids linked to glycerol
ester linkage = between OH & COOH
Esterification-formation of esters
hydroxyl
carboxyl
ester
(alcohol)
(acid)
AP Biology
Fats store energy
Long HC chain
polar or non-polar?
hydrophilic or hydrophobic?
Function:
energy storage – less weight but morecalories
concentrated
all H-C!
2x as much as carbohydrates
cushion organs
insulates body
think whale blubber!
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 tocardiovascular disease(atherosclerosis)= plaque deposits
AP Biology
Unsaturated fats
C=C double bonds inthe fatty acids
plant & fish fats
vegetable oils
liquid at room temperature
the kinks made by doublebonded C prevent themolecules from packingtightly together
AP Biology
Saturated vs. unsaturated
saturated
unsaturated
AP Biology
Phospholipids
Structure:
glycerol + 2 fatty acids + PO4
PO4 = negatively charged
(Acts like an acid-H3PO4)
AP Biology
Phospholipids
Hydrophobic or hydrophilic?
fatty acid tails =
PO4 head =
“repelled by water”
“attracted to water”
hydrophobic
hydrophilic
AP Biology
Phospholipids in water
Hydrophilic heads “attracted” to H2O
Hydrophobic tails “hide” from H2O
can self-assemble into “bubbles”
bubble = “micelle”
can also form a phospholipid bilayer
early evolutionary stage of cell?
bilayer
water
water
AP Biology
Why is this important?
Phospholipids create a barrier in water
define outside vs. inside
they make cell membranes!
AP Biology
Steroids
Structure:
4 fused C rings + ??
different steroids created by attaching differentfunctional groups to rings
different structure creates different function
examples: cholesterol, sex hormones
cholesterol
AP Biology
Cholesterol
Important cell component
animal cell membranes
precursor of all other steroids
including vertebrate sex hormones
high levels in blood may contribute tocardiovascular disease
AP Biology
Cholesterol
helps keepcell membranesfluid & flexible
Important component of cell membrane
AP Biology
From Cholesterol Sex Hormones
What a big difference a few atoms can make!
AP Biology
Saponification
Alkaline (basic) hydrolysis of a fat –yields the salt of fatty acids (soap)
AP Biology
Since a soap has a hydophobic end(fatty acid tails) and a hydrophilic end(Salt part) they remove dirt (grease) anddissolve in water
AP Biology
Hydrogenation
Oils (vegetable oil) can be converted toa more solid form by hydrogenation(adding H2) to unsaturated oils.
Ex. peanut oil in
peanut butter
Vegetable spreads
AP Biology
Trans fats
In the process of hydrogenation, transfats may be formed
They can increase the bad cholesterolleading to heart disease.
