Download 1 - UCSB CLAS

CHEM 109C – Zhang
CLAS, F10
Lipids - KEY
1. Indicate which class of lipids each of the following belongs to.
a.
A fat, saturated triacylglycerol, simple (tristearin)
b.
A vitamin or a terpene (Vitamin A, 20 Cs)
c.
A prostaglandin (PGE1)
d.
A steroid or a hormone (cortisone)
e.
A fatty acid or polyunsaturated fatty acid (arachidonic acid)
f.
A wax/ester of fatty acid and long chain alcohol (component of
spermaceti wax)
g.
An oil, saturated triacylglycerol, simple (trilinoleic)
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CHEM 109C – Zhang
CLAS, F10
Lipids - KEY
h.
A membrane lipid, phosphatidylcholine
2. What fatty acids are produced by the hydrolysis of 2-oleyl-1,3-distearylglycerol?
O
O
2
O
H
16
stearic acid
O
16
O
3 H2O
O
O
O
7
H
O
7
O
7
oleic acid
16
7
OH
OH
HO
glycerol
3. Spermaceti is a
wax
from a sperm whale which contains as a major
component hexadecyl hexadecanoate. Draw hexadecyl hexadecanoate.
O
O
15
4. Cembrene is a
14
diterpene
.
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CHEM 109C – Zhang
CLAS, F10
Lipids - KEY
C20H32
Be able to mark the isoprene units – below shown with dotted lines or colors
5. (Ch 26 # 1 & 3) Which of each of the following pairs of fatty acids or fats would
have the higher melting point and explain why.
a. palmitic acid & stearic acid
O
O
HO
HO
16
14 <
63
oC
oC
69
18 Cs so more van der Waal’s IMF, higher MP
b. palmitic acid & palmitoleic acid
O
O
HO
7
HO
14 >
oC
63
0 oC
saturated fatty acid so more van der Waal’s IMF, higher MP
c. oleic acid & linoleic acid
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CHEM 109C – Zhang
CLAS, F10
Lipids - KEY
O
O
HO
HO
7
7
7
>
13
-5 oC
only one double bond so more van der Waal’s IMF, higher MP
oC
d. glyceryl tripalmitoleate & glyceryl tripalmitate
fats made with…
palmitoleic acid & palmitic acid
O
O
HO
7
HO
14
<
oC
oC
0
63
saturated fatty acid, so saturated fat which has more van der Waal’s
IMF, higher MP.
Identifying Lipids (nonpolar compounds)
- Fatty acids
Long chain carboxylic acids (Table 26.1)
-
Fats
Triacylglycerols (glycerol + 3 fatty acids (0-1 double bond) → triester) simple &
mixed – solid or semi-solid at RT
-
Oils
Triacylglycerols (glycerol + 3 fatty acids (1+ double bond) → triester) simple &
mixed – liquid at RT
-
Waxes
Ester of fatty acid and long chain alcohol
-
Phospholipids (membrane lipids)
o Phosphoacylglycerol:
Fat where one fatty acid has been replaced by phosphoric acid
Phosphoacyldiester
Phosphoacylglycerol where phosphate forms ester with another group…
phosphatidylethanolamine (a cephalin)
phosphatidylcholine (a lecithin)
phosphatidylserine
o Sphingolipid:
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CHEM 109C – Zhang
CLAS, F10
Lipids - KEY
Phospholipid where amino alcohol (sphingosine) is backbone instead of
glycerol
sphingomyelin
-
Prostaglandins
5 member ring with 2 substituents (7-C carboxylic acid group (R1) and an 8-C
hydrocarbon (R2))
-
Terpenes
Contains Cs in multiples of 5 (Table 26.3)
- Steroids
Have 4 fused rings (A, B & C are cyclohexane rings and D is a cyclopentane)
Mechanisms:
Oxidation of fats and oils by oxygen
Synthesis of prostaglandins from arachidonic acid
Chemistry of vision – isomerization of retinal
Biosynthesis of terpenes
Synthesis of isopentyl pyrophosphate from acetyl-CoA and malonyl-CoA
Synthesis of dimethylallyl pyrophosphate from isopentyl pyrophosphate
Synthesis of terpenes from isopentyl pyrophosphate & dimethylallyl
pyrophosphate
Synthesis of cholesterol from squalene
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