lipids
TRANSCRIPT
Lipids
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Lipids
• Biomolecules soluble in organic solvents
• Roles– Nutritional– Structural– regulatory
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Types of Lipids
• Glycerol-based
• Sphingolipids
• Steroids
• Eicosanoids/leukotrienes
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Storage Lipids
• http://web.indstate.edu/thcme/mwking/lipids.html#triglycerides
• Fatty acids – See chart on website– Saturated and Unsaturated
• Relationship to melting point
• Triacylglycerides– Glycerol + 3 fatty acids
• Waxes
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Glycerol based fats
CH2
CH
CH2 OH
OH
OH
• Glycerol on the left• Esterifies to 3 fatty
acids
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Triacylglyerides
• Glycerol in blue• Fatty acids in red• Condensation
produces 3 water molecules
• Very nonpolar…excludes water
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Lipids in Membranes:
• Phospholipids
• Cholesterol
• Glycolipds: Sugar group attached
• Proteins: either integral or peripheral
• Sphingolipids
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Phosphoacylglycerols
• Glycerol esterified to 2 fatty acids.
• Third position is phosphate
• Other end of phosphate can combine with other molecules to form various derivatives
• amphipathic
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Phosphoacylglycerols
CH2
CH
CH2 O
O
O
R1
O
O
R2
PO
O
O
X
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Derivatives of Phosphoacylglycerols (PAG)
CH2
CH
CH2 O
O
O
R1
O
O
R2
PO
O
O
X
X- structure Name PAG name
H hydrogen Phosphatidic acid
serine Phosphatidyl serine
choline Phosphatidyl choline (lecithin)
ethanolamine Phosphatidyl ethanolamie
inositol Phosphatidyl inositol
H3N+ OH
O
O
OH
CH3N+
CH3
CH3
OHH3N+
H
OH
OH
H H
OH
H
OH
OH
HOH
H
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Phosphatidyl choline with fatty acids as oleate and palmitate
O
CH3N+CH3
CH3
O
(CH2)14 CH3O
O
O
(CH2)7 CH
CH
(CH2)7 CH3
CH2
CH
CH2
OP
O
O
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Sphingolipids
• Sphingosine instead of glycerol• Derivatized at ester C1• Fatty acids added at amine• Different types are found in plasma
membrane and myelin sheaths• Gangliosides
– cell to cell interactions– antigenic
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Sphingosine
OH CH
CH
CH
(CH2)12-CH3
CH NH2
CH2OH
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Sphingolipids
OH CH
CH
CH
(CH2)12-CH3
CH NH
CH2
R
O
OX
X name
H ceramide
monosaccharide cerebroside
carbohydrate ganglioside
sphingomyelin
O
CH3N+CH3
CH3
P O
O
O
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Sphingophospholipid with choline and the fatty acid as linolenic
O
(CH2)7 CH CH CH2CH CH CH2 CH CHCH2CH3NH
CH3N+CH3
CH3
O
OH CH
CH
CH
(CH2)12-CH3
CH
CH2OP
O
O
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Cholesterol
OH
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Role of Cholesterol• Keeps the lipids in membrane from
aggregrating: Keeps the membrane intact as a bilayer
• Precursor to Bile Acids– Act as detergentsto dissolve dietary fats– Fats can be broken better by enzymes
• Precursor to steroid hormones that regulate gene expression
• Precursor to Vitamin D
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Good vs. Bad Cholesterol
• Related to lipoproteins (protein + lipid complexes)
• Dietary excess fat is packaged into VLDL
• Fat cells (adipose cells) take these up convert to fatty acids
• Some VLDL is converted to LDL
• LDL is very rich in Cholesterol
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LDL
• Too much LDL can circulate in the blood
• Build up in arteries; lead to heart attack
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HDL
• Another lipoprotein that converts cholesterol into a lipoprotein that returns to the liver ; Removes cholesterol out of the bloodstream;
• believed to prevent heart attacks
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Ratio of LDL to HDL• LDL cholesterol of less than 100 mg/dL is
the optimal level. Less than 130 mg/dL is near optimal for most people.
• A high LDL level (more than 160 mg/dL or 130 mg/dL or above if you have two or more risk factors for cardiovascular disease) reflects an increased risk of heart disease
• Low HDL cholesterol levels [less than 40 mg/dL] is thought to increase the risk for heart disease.
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Steroid hormones
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Eicosanoids• Prostaglandins: different types
– Some stimulate contraction of smooth muscle during menstruation and labor
– Others produce fever and inflammation and pain
• Thromboxanes: act in the formation of blood clot
• Leukotrienes: induces contraction of the muscle lining the lungs– overproduction leads to asthma
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Eicosanoids/Leukotrienes
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