Lipids
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Classification
Properties
Function
Basic Structure
Thought for today: If someone calls you a “FAT HEAD”,
first compliment them on their biochemical insight,
before you punch them in their fat head”.
What is a Lipid?
Any substance that is insoluble in water but
soluble in organic solvents
Does this mean any water insoluble compound?
Yes
What are some examples I would recognize?
Cholesterol….a steroid
Stearic acid….a saturated fatty acid
Oleic acid…an unsaturated fatty acid
Bees wax….a fatty acid ester
Vitamins A,D,E,K…the fat-soluble vitamins
Tripalmitin…a triacylglycerol
Lecithin…a membrane glycerophospholipid
Classifications (all lipids)
Simple vs Complex
Charged vs Neutral
Fatty Acids
Saturated vs Unsaturated
Esterified vs Non-esterified
Odd chain vs Even chain
Anatomy of a C14 Saturated Fatty acid
Non-Polar
CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2COO-
Charged carboxyl
Methyl end group
Fatty Acids
Rule: A lipid begins when water insolubility begins
CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2COOH
Not yet
Getting There
Whoa!
C12 saturated fatty acid…..Lauric acid
C14 …..Myristic acid
C16…..Palmitic acid
C18…..Stearic acid
C20…..Arachidic
Unsaturated Fatty Acid
Rule: Double bonds in fatty acids are always CIS
CH2
H H
C=C
CH2
Rule: Double bonds are always separated
9
by a -CH2- group 12
10
CH2
H H
C=C
11
H H
CH2 C=C CH2
3
2
1
Rule: Double bonds are always numbered 3 apart
Example 9,12 means a double bond on C9 and C12
Rule: Cis double bonds put Kinks in fatty acid chains.
Corr: The more the double bonds the greater the bend
Cis D.B.
Cis D.B.
Saturated
1 D.B.
2 D.B.
Trans Fatty Acids are to be avoided for health reasons
Rule: Double Bonds lower melting point of a fatty acid
Corr: The more double bonds, the lower the melting point
Room Temperature
Melting
Temperature
All Unsaturated
fats are oils at room
temperature
0
1
2
3
D.B.
4
Complex Lipids
What are they?
Lipids molecules comprised of more than one
component….the individual components are readily
disassembled by acid or base hydrolysis
Give me some examples
Acylglycerols = fatty acids esterified to glycerol
Glycerol
O
Monoacylglycerol
H
O H C-OH
-O-C-CH2C-R
Diacylglycerol
HO-CH O
R-CH2C-O
-O-C-CH2C-R Triacylglycerol
H C-OH
H
(Triglyceride)
Triacylglycerol
Saturated
MonoUnsaturated
Glycerophospholipids = 2 fatty acids esterified to
glycerol with phosphate and an amine group
HO-CH2CH2NH3+
O
O CH2O C-R
R-C O- CH O
CH2-O P O
O
Phosphatidate
MEMBRANE
LIPIDS
Ethanolamine
+
HO-CH2CH2N(CH3)3
Choline
H
HO-CH2CCOO+NH3
HO OH
Serine
HO
OH
.
HO
OH
Inositol
HO
Cholesterol