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Lipids
with fatty acids Fats and oils (trigycerides) Phospholipids Waxes Sphingolipids Lipids without fatty acids Steroids
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Long-chain
carboxylic acids Insoluble in water Typically 14-22 carbon atoms (even number) Some contain double bonds corn oil contains 86% unsaturated fatty acids and 14% saturated fatty acids 3
Contain
only single C–C bonds Closely packed Fit closely in regular pattern COOH COOH COOH
Strong
attractions between chains High melting points Solids at room temperature
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Contain
one or more double C=C bonds Nonlinear chains do not allow molecules to pack closely Few interactions between chains Low melting points Liquids at room temperature Cis double bonds H
H C C
COOH
cis double bond
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COOH palmitic acid, a saturated acid COOH palmitoleic acid, an unsaturated fatty acid
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Polyunsaturated
bond
: More than 1 double
How would the melting point of stearic acid compare to the melting points of oleic acid and linoleic acid? Assign the melting points of –17°C, 13°C, and 69°C to the correct fatty acid. Explain. stearic acid (18 C) saturated oleic acid (18 C) one double bond linoleic acid (18 C) two double bonds
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Stearic
Oleic
Acid
Acid
Linoleic
Acid
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Stearic acid is saturated and would have a higher melting point than the unsaturated fatty acids. Because linoleic has two double bonds, it would have a lower mp than oleic acid, which has one double bond. stearic acid mp 69°C oleic acid mp 13°C linoleic acid mp -17°C 10
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Formed from glycerol and fatty acids O CH2 OH CH
OH
CH 2
OH
HO C O +
HO C (CH 2)14CH 3 O HO C
glycerol
(CH 2)14CH 3
(CH 2)14CH 3
palmitic acid (a fatty acid) 13
Esters of glycerol and fatty acids ester bonds O CH2
O
C
(CH2)14CH3 + H2O
O CH CH2
O O
C (CH2)14CH3 O C
+ H2O
(CH2)14CH3 +
H2O 14
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•
Lipid made from two types of molecules • Fatty acid • Glycerol
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•
One to three fatty acid chains are joined to a single glycerol molecule through dehydration synthesis Triglycerides are most well-known • Contain three fatty acid chains
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Fats
are solid at room temperature and usually have saturated fatty acids Oils are liquid at room temperature and have more unsaturated fatty acids
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1)
2) 3) 4) 5) 6)
Energy: One gram of fat contains TWICE as much energy (378 kJ) as one gram of carbohydrates (168 kJ). Storage of energy (adipose tissue) Insulation Shock absorber Aids in absorption of fat soluble vitamins (A,D, E and K) Building block
Hydrogenation Unsaturated
compounds react with H2 Ni or Pt catalyst C=C bonds C–C bonds
Hydrolysis Split
by water and acid or enzyme catalyst Produce glycerol and 3 fatty acids
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O CH2
O
C
(CH 2)5CH CH(CH2)7CH3
O CH CH 2
O O
C O C
(CH2)5CH CH(CH2)7CH 3
+ 3 H2
Ni
(CH2)5CH CH(CH2)7CH3
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O CH2
O
C
(CH2)14CH3
O CH
O
C (CH 2)14CH 3 O
CH 2 O C (CH2)14CH 3 Hydrogenation converts double bonds in oils to single bonds. The solid products are used to make margarine and other hydrogenated items.
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Triglycerides split into glycerol and three fatty acids (H+ or enzyme catalyst) O CH2
O
C
(CH2)14CH 3
O CH CH 2
O O
H+
C (CH2)14CH3 O C
+3 H2O
(CH2)14CH 3 CH2 OH CH
OH
CH2
OH
O +
3 HO C
(CH 2)14CH3 21
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Most
abundant lipids in cell membranes Control cell permeability FATTY ACID glycerol
FATTY ACID PO4
Amino alcohol 23
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Abundant
in brain and nerve tissues Found in egg yolk, what germ, yeast O CH 2 O C (CH 2)14CH 3 O CH O
C O
(CH2)14CH3
+ CH 2 O P O CH2CH 2N(CH 3)3 O-
choline, an amino alcohol 25
Esters of an 18-carbon alcohol sphingosine FATTY ACID sphingosine
PO4
Amino alcohol 26
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Found in the myelin sheath CH3(CH2)12CH=CH –CH–OH sphingosine
O ǁ fatty acid CH–NH –C –(CH2)14CH3 O ǁ + CH2 –O –P –O –CH2CH2 –N–(CH3)3 ǁ O– choline 27
long
chain fatty acids linked to carbon rings or alcohols Hydrophobic molecules Uses: waterproof coating on plant and animal parts (cutin on outside of plant leaves, wax on feathers, beeswax)
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Waxes from bird feathers
Bee wax
Hydrophobic molecules containing Steroid nucleus of 4 fused hydrocarbon rings and functional groups
Steroid nucleus 3 cyclohexane rings 1 cyclopentane ring
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Most
abundant steroid in the body Add methyl CH3- groups, alkyl chain, and -OH to steroid nucleus CH 3 CH3
CH3 CH 3
CH3
HO 33
Two
types of cholesterol packaging: - Low Density Lipoproteins (LDL’s) - High Density Lipoproteins (HDL’s)
Lipoproteins (LIP-oh-PRO-teens): clusters of lipids associated with protein that serve as transport vehicles for lipids in blood and lymph.
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“Bad” cholesterol
(linked to clogging of
arteries) 70% of cholesterol intake LDLs bind to receptor sites on cell membranes and are removed from blood by liver but excess LDLs deposit on walls of arteries causing plaque which may prevent blood flow causing strokes or heart attacks (ATHEROSCLEROSIS)
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“Good” cholesterol carry
bad cholesterol to liver to break it down therefore lower blood cholesterol levels should have 35 mg/100 mL of HDLs or more in blood
Cellular Myelin Bile
membranes
sheath, brain, and nerve tissue
salts
Hormones Vitamin
D
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Synthesized Stored
in the gallbladder
Secreted Mix
in the liver from cholesterol
into small intestine
with fats to break them part
Emsulsify
fat particles
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cholic acid, a bile acid CH3 OH CH3 CH3
HO
O C N CH2 COO- Na+ H gycine, an amino acid
OH sodium glycocholate, a bile salt
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Chemical
messengers in cells Sex hormones Androgens in males (testosterone) Estrogens in females (estradiol) Adrenocorticosteroids from adrenal glands mineralocorticoids (electrolyte balance) glucocorticoids regulate glucose level
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CH3 OH CH3
O
CH3 OH CH3
HO t e st ost e r on e
e st r ad iol
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Identify each lipid as: (1) phospholipid (2) steroid (3) triglyceride (4) sphingolipid A. Cholesterol B. Glycerol, 2 fatty acids, phosphate, and choline C. Glyceryl tristearate D. Sphingosine, fatty acid, phosphate, and choline E. Estradiol F. Bile salts G. Most of plasma membranes
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A. B. C. D. E. F. G.
2 steroid phospholipid 3 triglyceride 4 sphingolipid 2 steroid 2 steroid 1 phospholipid
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Surround Lipid
cells
bilayer of phospholipids
Nonpolar
hydrocarbon tails in center
Polar
(hydrophilic) heads on outside
Some
unsaturated fatty acids give flexibility
Keep
aqueous contents inside
Allow
certain biochemicals to pass through
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Polar sections
Nonpolar tails
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Cholesterol
molecules add strength Glycolipids on surface communicate with other cells Proteins embedded in bilayer move certain substances (water, K+, Cl-, HCO3-) across the cell membrane Proteins on surface act as receptors for hormones and other biochemicals
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