Lipids
 Hydrophobic molecules
 Do NOT consist of polymers
 Function:
energy storage
 cell membrane
 protection - cushions organs
 insulates body

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2003-2004
Structure of Fat
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What are lipids composed of?
1 glycerol + 3 fatty acids  lipids (triglycerides)
 Vary in length and number and location
of double bonds
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How are lipids made and broken down?
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How are lipids made?
Broken down?
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Saturated Fats
 Mostly animal fats

solid at room
temperature
 Saturated with
hydrogen
 All single bonds
 Can be tightly
packed
 Limit the amount in
your diet
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Unsaturated fats
 Plant, vegetable & fish
fats (oils)

liquid at room
temperature
 the fat molecules
don’t stack tightly
together
 Double bond causes a
kink
 Better choice in your
diet
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Saturated vs. Unsaturated Examples
saturated
unsaturated
 Meat
 Butter
 Ice Cream
 Cookies
 Animal Fat
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 Olive oil
 Canola Oil
 Avocado
 Nuts
 Seafood
 Soy
2003-2004
Other lipids in biology
 Cell membranes are made out of phospholipids




2 fatty acid tails & a phosphate group
heads are on the outside touching water
 “like” water (hydrophilic)
tails are on inside away from water
 “scared” of water (hydrophobic)
forms a barrier
between the cell
& the outside
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2003-2004
 Phospholipid structure
CH2
+
N(CH )
3 3
Choline
CH2
O
O
P
O–
Phosphate
O
CH2
CH
O
O
C
O C
CH2
Glycerol
O
Fatty acids
Hydrophilic
head
Hydrophobic
tails
Figure 5.13
(a) Structural formula
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(b) Space-filling model
(c) Phospholipid
symbol
10
 The structure of phospholipids

Results in a bilayer arrangement found in
cell membranes
WATER
Hydrophilic
head
WATER
Hydrophobic
tail
Figure 5.14
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Other lipids in biology
 Steroids, Ex: Cholesterol
Carbon skeleton of 4 fused rings
 good molecule in cell membranes
 make hormones from it

 including sex hormones

but too much cholesterol in blood may
lead to heart disease
H3C
CH3
CH3
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HO
CH3
CH3
Other lipids in biology
 Waxes
Bees, ears, shiny leaves,
shiny feathers, hair
 Repels water
 For protection

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