Lipids “Fat, what good is it?”

Lipids Biomolecules soluble in organic solvents Roles –Nutritional –Structural –regulatory

Types of Lipids Glycerol-based Sphingolipids Steroids Eicosanoids/leukotrienes

Storage Lipids Fatty acids –Saturated and Unsaturated Relationship to melting point Triacylglycerides –Glycerol + 3 fatty acids Waxes

Glycerol based fats Glycerol on the left Esterifies to 3 fatty acids

Triacylglyerides Glycerol in blue Fatty acids in red Condensation produces 3 water molecules Very nonpolar…excludes water

Lipids in Membranes: Phospholipids Cholesterol Glycolipds: Sugar group attached Proteins: either integral or peripheral Sphingolipids

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

Phosphoacylglycerols

Derivatives of Phosphoacylglycerols (PAG) X- structureNamePAG name Hhydrogen Phosphatidic acid serine Phosphatidyl serine choline Phosphatidyl choline (lecithin) ethanolamine Phosphatidyl ethanolamie inositol Phosphatidyl inositol

Phosphatidyl choline with fatty acids as oleate and palmitate

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

Sphingosine

Sphingolipids Xname Hceramide monosaccharidecerebroside carbohydrateganglioside sphingomyelin

Sphingophospholipid with choline and the fatty acid as linolenic

Cholesterol

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

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

LDL Too much LDL can circulate in the blood Build up in arteries; lead to heart attack

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

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.

Steroid hormones

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

Eicosanoids/Leukotrienes