Fatty Acids A straight hydrocarbon chain Saturation o CH3 CH2 CH2 CH2 CH2 COOH o 4 24 carbon long o 14 or more C nutritionally significant o most are even numbers of carbon o Saturated fatty acids o Monosaturated Fatty Acids All C s are saturated with H s NO DOUBLE BONDS C C One double bond C C Examples olive oil canola oil Multiple double bonds Cis form is predominant o Polysaturated Fatty Acids Hydrogenation fat to make it solid at room temperature o Is the process of adding hydrogen s to an unsaturated o Often used in commercially processed foods Ex Cracker cookies snack cakes etc o Forms trans fat How to name a fatty acid Nomenclature very important Count the number of C s Count the number of double bonds Name according to omega or alpha end CH3 omega end COOH alpha end o Ex CH3 CH2 CH2 CH CH CH2 CH2 CH CH CH2 COOH C DB 11 2 4 or 11 2n4 this is counting from omega 11 2 3 7 or 11 2 3 7 this is counting from side alpha side Essential Fatty Acids o We lack enzymes to add double bond beyond 9 Linoleic Acid 18 2 6 or 18 2 9 12 Linoleic Acid 18 3 3 or 18 3 9 12 15 Vegetable oil corn sunflower nuts peanuts flax seed oil walnuts soy beans Eicosanoids derived from arachidonic acid A hormone like substance o Modulation of Blood pressure Platelet aggregation Immune system Nervous system Smooth muscle contraction veins Families Synthesized from drawing o Prostacyclin o Thromboxanes o Leukotrienes o Arachidonate Acid makes prostacyclin thromboxanes o Eicosatrienoic Acid makes prostacyclin thromboxanes o Eicosapentanoic Acid makes prostacyclin leukotrines thromboxanes leukotrines Triglycerides Main fatty compound in diet Glycerol backbone 3 carbon chain Three fatty acids Phospholipids Glycolipids Sterols Glycerol backbone One or more fatty acid One phosphate Lipid and carbohydrate Function cell membrane structure Steroid nucleus Cholesterol essential component for all membranes especially nerve tissue precursor for o Bile acids o Steroidal sex hormones o Adrenocortical hormone o Vitamin D Lipid Digestion begins in mouth Lingual lipase gastric lipase o Secrete at base of tongue and chief cells of stomach o Stable at a low pH o Efficient digestion of milk fat excellent for infants Biliary Emulsification o Emulsification Dispersion of fat in an aqueous solution This allows for lipase action Emulsifying agent o Bile Salts o these are 2 ways to help lipids be digested in intestines Lipolysis o Three main enzymes for digestion Pancreatic Lipase Breaks down triglyceride into 1 2 diacylglycerol and fatty acid the 1 2 diacyglycerol then breaks down even to form monoglycerol and free fatty acid then the monoglycerol breaks down to form glycerol and fatty acid Think of it like this the triglyceride has 3 fatty acid chains hanging off of it pancreatic lipase is like a scissor that cuts fatty acid one at a time until glycerol is all by itself This enzyme simply breaks down cholesterol ester into free cholesterol and free fatty acid Breaks down lecithin into lysolecithin and Cholesterol Esterase Lecithinase fatty acid o Final product in intestines fatty acid glycerol cholesterol lysolecithin Lipid Absorption Micelle Formation surrounded by bile salts o Micelle fatty elements and fat soluble vitamins o Helps body interact with fatty acids o Fatty elements and vitamins are absorbed by passive diffusion at distal duodenum and jejunum Lipoproteins Inside the enterocyte o Bile salts absorbed in ileum and returned to liver via 12 C and other fatty EHC o Long chain fatty acids compounds activated with coenzyme A o Reformation of triglycerides cholesterol esters and phospholipids remember they were broken down by lipolysis Chylomicron albumin o Triglyceride fatty components proteins o Short chain fatty acids pass to the blood and attach to Complexes which carry lipid products in the blood and lymph Chylomicron to various tissues o Formation o Composition from diet lipids Synthesis in enterocytes from exogenous fats Released into lymph Apoproteins A B C E 1 2 Triglycerides 80 PL cholesterol 15 Largest lipoprotein w lowest density 90 100 nm the more protein the heavier it is o Size o Function Transport exogenous triglycerides to tissues Lipoprotein Lipase LPL acids and glycerol tissues Hydrolyzes breaks down TG to free fatty Free fatty acids and glycerol absorbed into Remains after TG hydrolysis left overs Taken up by hepatocytes via receptor mediated o Chylomicron remnant Very Low Density Lipoprotein VLDL endocytosis o Formation o Compostion Synthesized in liver Released into blood Apoproteins B C 8 Triglycerdies 50 Cholesterol 20 Phospholipids 20 o Size 30 90 nm o Function Transports endogenous lipid from liver to extra Lipoprotein Lipase LPL hepatic tissues Hydrolyzes TG to free fatty acids and Transports fats that we make from liver glycerol Intermediate Density Lipoprotein IDL Transient very short lived o Formation from VLDL after TG hydrolysis o Function formed into LDL after TG hydrolysis via LPL o Formation from IDL after TG hydrolysis o Function Low Density Lipoprotein LDL o Composition Delivers cholesterol to non hepatic tissues Uptake via receptor mediated endocytosis Apoproteins B 100 21 Triglycerides 9 Cholesterol 50 Phospholipids 23 o Size 20 25 nm o Receptor Mediated Endocytosis Receptors located in clatharin coated pits Receptors are specific for proteins LDL have apo B 100 Forms vesicle LDL and receptor binds Receptor and LDL complex internalized Vesicle fuses with lysosome Lysosome changes pH ApoB degraded to amino acids Cholesterol released into cell Receptor returns to surface Regulation HMG CoA reductase activity Rate limiting enzyme for cholesterol More cholesterol in cell lowers synthesis enzyme activity LDL receptor synthesis If cholesterol levels in cell are high it will decrease LDL receptor synthesis Therefore increase levels of dietary cholesterol in blood High Density Lipoproteins HDL o Formation liver and intestines o Composition Apoprotein A C D E 50 Triglycerdie 3 Cholesterol 20 Phospholipid 30 o Size 5 25 nm o Function membranes or from other lipoproteins Removal of cholesterol from non hepatic tissues Lecithin cholesterol acyltransferase LCAT Allows HDL to pick up cholesterol from cell Apo A1 protein binds to LCAT receptor Cholesterol cholesterol ester CE Phospholipid lysolecithin HDL transports CE to tissues binds to albumin Lysolecithin LIPOPROTEIN SIZES IN COMPARISON Chylomicron VLDL LDL HDL Cholesterol Synthesis drawing synthesized Location o Liver 10 o A little more than
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