Chapter 23 Study Guide—Lipids
PROPERTIES:
1. Insoluble in water
2. Soluble in organic liquids
3. Composed of C, H, O and sometimes N and P.
4. Take part in plant and animal metabolism
5. Yield fatty acids upon hydrolysis
FATTY ACIDS:
1. Straight chain of carbons with carboxylic acid on the end.
2. Always contains an even number of carbons.
3. Can be saturated(no double bonds), monounsaturated(1 double bond),
polyunsaturated(more than one double bond).
4. Double bonds are all cis. Usually occurring at C-9(C-12, C-15). Not conjugated.
5. Linoleic acid is the only essential fatty acid.
6. The more unsaturation the lower the melting point(unsaturated fatty acid--liquid;
saturated fatty acid--solid).
FATS AND OILS:
1. Fats and oils are made of a glycerol molecule and three fatty acids(triglyceride).
2. Fats are usually white solids(saturated--no double bonds).
3. Oils are usually yellow liquids(unsaturated--1 or more double bond).
4. Fats/Oils when hydrolyzed give 3 fatty acids and glycerol.
5. Oils when hydrogenated yield fats.
6. Fats/Oils when saponified(NaOH/KOH) yield 3 soap molecules and glycerol.
SOAPS:
1. Bar soaps come from saponification of fats/oils with NaOH.
2. Soft soaps come from saponification of fats/oils with KOH.
DETERGENTS:
1. Composed of the sodium salts of high molecular weight alcohol sulfates.
2. Biodegradable detergents are made of straight chains.
3. Nonbiodegradable detergents are made of branched alcohols.
WAXES:
1. Made from the reaction of a high molecular weight fatty acid and high molecular weight
alcohol(ester).
2. Waxes are insoluble in water, nonreactive and flexible.
3. Excellent as protective coatings in foods, beverages, cars, floors, fur and feathers.
TERPENES:
1. Made from 5 Carbon repeating unit with 2 double bonds(isoprene, rubber).
2. Examples—myrcene, a-farnesene, limonene, pinene, geraniol, menthol, zingberene, selinene,
caryophyllene, squalene,
COMPLEX LIPIDS:
1. Contain simple lipids plus nitrogen and phosphorous.
2. Phospholipids(main constituent of lipid bilayer) and Phosphosphingosides
(sphingomyelin) and glycolipids(brain tissue). Steroids, prostaglandins(immune system)
and cholesterol.
4. Phosphatidyl choline a.k.a. lecithin are good emulsifying agents. They are found in
eggs and are used to emulsify mayonnaise.
5. Dipalmitoyl lecithin is a good surfactant(surface acting agent). It cleans the lungs of
newborn babies. In premature infants DPL is often missing leading to respiratory
distress syndrome(RDS).
6. Removal of one of the fatty acids from lecithin leads to lysolecithin. This process is
catalyzed by an enzyme, lecithinase A, which is found in many snake venoms.
Lysolecithin causes hemolysis(destruction of red blood cells).
7. Cephalins are important in the clotting of blood.
8. Niemenn-Pick disease. Know when it occurs, why it occurs, the results and the
enzyme.
9. Multiple sclerosis. Know the relationship to sphingo lipids.
10. Gaucher’s disease. Know when it occurs, why it occurs, the results, the adult form and
the enzyme.
11. Tay-Sach’s disease. Know when it occurs, why it occurs, the results and the enzyme.
12. Steroids—cholesterol, testosterone, progesterone, estradiol, cortisone
13. Prostaglandins. Where they are isolated? What functions they have in the body?
What have they been used to treat?
14. Prostacyclin and Thromboxanes role in blood clotting and the vascular system.
15. Lipid bilayer
N
E
G
J
I
C
TXB2
O
estradiol
A
fat
Q
prostacyclin
P
inositol
H
sphingomyelin
serine
L
arachidonic acid
M
choline
K
ethanolamine
F
lecithin(phosphatidylcholine)
D
OH
CH3
M.
phosphoglyceride
cholesterol
B
glycolipid
testosterone
prostaglandin E1(PGE1)
cephalin(phosphatidylethanolamine)
OH
N.
CH3
COOH
HO
O
O.
CH3
O
CH3
OH
OH
P.
CH3
HO
Q.
HO
COOH
O
OH
OH
CH3
CH
CH3
CH2 CH2 CH2 CH
CH3
A.
g
l
y
c
e
r
o
l
fatty acid
C.
fatty acid
F.
fatty acid
galactose
fatty acid
D.
phosphoric acid-choline
g
l
y
c
e
r
o
l
E.
s
p
h
i
n
g
o
s
i
n
e
phosphoric acid-nitrogen compound
g
l
y
c
e
r
o
l
fatty acid
B.
fatty acid
g
l
y
c
e
r
o
l
fatty acid
fatty acid
fatty acid
fatty acid
phosph. acid-ethanolamine
O
G.
COOH
OH
H H
H OH
OHOH
H H
H
OH
H.
choline-phosphoric acid
s
p
h
i
n
g
o
s
i
n
e
I.
OH
J.
NH2
HO-CH2-CH-COOH
OH
+
HOCH2 -CH2-N-(CH3) 3OH-
K.
HO-CH2-CH2-NH2
fatty acid
COOH
L.
OH