CHEM 109C – ZhangCLAS, F10
Lipids - KEY
- Indicate which class of lipids each of the following belongs to.
A fat, saturated triacylglycerol, simple (tristearin)
A vitamin or a terpene (Vitamin A, 20 Cs)
A prostaglandin (PGE1)
A steroid or a hormone (cortisone)
A fatty acid or polyunsaturated fatty acid (arachidonic acid)
A wax/ester of fatty acid and long chain alcohol (component of spermaceti wax)
An oil, saturated triacylglycerol, simple (trilinoleic)
A membrane lipid, phosphatidylcholine
- What fatty acids are produced by the hydrolysis of 2-oleyl-1,3-distearylglycerol?
- Spermaceti is a wax from a sperm whale which contains as a major component hexadecyl hexadecanoate. Draw hexadecyl hexadecanoate.
- Cembrene is a diterpene.
C20H32
Be able to mark the isoprene units – below shown with dotted lines or colors
- (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.
- palmitic acid & stearic acid
63 oC69 oC
18 Cs so more van der Waal’s IMF, higher MP
- palmitic acid & palmitoleic acid
63 oC0oC
saturated fatty acidso more van der Waal’s IMF, higher MP
- oleic acid & linoleic acid
13 oC-5oC
onlyone double bondso more van der Waal’s IMF, higher MP
- glyceryl tripalmitoleate & glyceryl tripalmitate
fats made with…
palmitoleic acid & palmitic acid
0 oC 63 oC
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)
- 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Fat where one fatty acid has been replaced by phosphoric acid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
- Sphingolipid:
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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