Lipids

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Lipids

• Fat, what good is it?

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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

• Fatty acids
• Saturated and Unsaturated
• Relationship to melting point
• Triacylglycerides
• Glycerol 3 fatty acids
• Waxes

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Glycerol based fats

• 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 nonpolarexcludes 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
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Derivatives of Phosphoacylglycerols (PAG)
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Phosphatidyl choline with fatty acids as oleate
and palmitate
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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
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Sphingolipids
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Sphingophospholipid with choline and the fatty
acid as linolenic
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Cholesterol
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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