Lipids z Classification z Structure z Functions Figures from Moran Principles of Biochemistry 4th 5th edition Lehninger Principles of Biochemistry 4th 5th Ed Voet Voet Biochemistry 3E Voet Voet Pratt Voet Pratt Fundamentals of Biochemistry 2E McKee McKee Biochemistry 5th Edition Tymozsko Biochemistry A short course Lipids p a heterogeneous g class of organic g molecules with marginal solubility in water hydrophobic Most lipid functions relate directly or indirectly to their hydrophobicity Lipid functions Biological membranes Energy storage triglycerides Electrical insulation impermeable for ions Ex myelin sheath of nerves Thermal h rma insulation nsu at on a adipose pos tissue t ssu low ow in n water wat r and an capillaries cap ar s Hydro insulation water repelling waxes Signaling cholesterol phosphatidylinositol phosphoinositides Hormone and vitamin p precursors Steroids Vitamins D E K A Digestion Ex bile acids emulsifiers Lipid Structure T Two structural t t l groups 1 Open chain Polar head groups with long non non polar polar aliphatic tails Fatty acids Phosphoacylglycerols Sphingolipids S hi li id Eicosanoids Waxes Faatty acid d derivattives Triacylglycerols Triacylglycerols 2 Fused ring compounds steroids lipid li id vitamins it i all are isoprenoids isoprene Lipid structure function Energy Storage and Membrane lipids CHOLESTEROL Storage lipids non polar Non polar Membrane lipids M b li id Amphiphilic hi hili Polar head Non polar tails Fatty Acids Saturated S t t d Stearate Unsaturated Oleate Fatty acids By presence and number of double bonds I Saturated no no double bonds II Unsaturated double bond s IIa Monounsaturated 1 IIb Poly unsaturated IIb P l d 2 or more Fatty acids Nomenclature 12 0 14 0 16 0 18 0 20 0 22 0 24 0 16 1 18 1 18 2 18 3 20 4 Common Laura 12 used My 14 Palm 16 to Stir 18 Arachnids 20 Fatty acids IUPAC Nomenclature Length of double bonds cys or trans position of bonds Length Double bonds 12 dodeca 0 anoate anoic acid dodecanoate dodecanoic acid 14 tetradeca 1 enoate enoic acid 16 hexadeca 2 dienoate dienoic acid 18 octadeca 18 t d 3 trienoate trienoic 3 ti t t i i acid id 20 eicosa 4 tetraenoate tetraenoic acid 5 pentaenoate pentaenoic pentaenoate pentaenoic acid t d octadecenoate t Saturated vs cys vs trans unsaturated Fatty acids Know how to d draw f f a structures by name and vice versa Cis conformation of double bonds Unsaturated Fatty acids Trans fat Almost never p produced naturally y found in hydrogenated vegetable oils in which unsaturation is in trans form Rigidifies the hydrocarbon tail in extended conformation Cis bond Causes a bend in the hydrocarbon tail 12 0 14 0 16 0 18 0 20 0 22 0 24 0 16 1 Esse ntial 18 1 18 2 18 3 6 3 20 4 Melting point of fatty acid layers increases with increasing chain length more rigid membranes But it decreases more dramatically with degree of unsaturation These rules also apply to biological membranes that y acid derivatives contain fatty Which of the fatty acids has the highest melting temperature more rigid 33 33 33 c 18 3 ni ol e in ns L l t ra al Ar ac l c ys al al l c ys L in ol hi d ei on ic ca ac c id id 1 8 2 A all A all cys cys Linoleic acid 18 2 B all cys Arachidonic acid 20 4 C all trans C all trans Linolenic 18 3 Linoleate 18 2 all cys 9 12 Octadecadienoate 20 5 EPA all cys 5 8 11 14 17 Eicosapentoenoic acid Practice at home Are these FA omega 3 or omega 6 Practice at home IUPAC Common IUPAC Common Storage lipids Triacylglycerols l l l triglycerides major components of fats and oils Glycerol Energy and thermo insulation molecule major dietary lipid Animal adipose p tissue Plant oil cells Triglycerides Is the main way to store chemical energy for long term long term Why not carbohydrates short term energy molecules Fatty y acids have 2 2 times higher g energetic g value per weight compared to carbohydrates 9 kcal g vs 4 kcal g Why Energy is gained by oxidation of organic molecules F tt acids Fatty id are less oxidized vs 1 kcal 1Cal food or large calorie 4 2kJoule glucose glucose Adipose tissues White FatFatnutrient storage thermoinsulation present in kids and adults Brown FatFatthermoregulation abundant in newborns and in hibernating mammals but scarce in adults Energyburning adipose tissue rich in mitochondria p produces heat Warm body Cold treated Cold treated body Why brown fat is brown Storage function of triglycerides TG Polar bears eat for several weeks in a winter time and then go without food for up to 8 months months yet remain active active give birth birth and nurse young while fasting Polar bears consume predominantly seal fat that consists almost exclusively of triacylglycerols The body mass of individual polar bears can more than triple over this period on a g fat diet and their bodies mayy consist of more than 50 percent p adipose p tissue high vesicular cells filled with fat During summer time polar bears don t eat as they satisfy all they dietary needs by burning 2 3 pounds of fat daily When polar bears dine exclusively on seal fat their cholesterol levels drop because of the protective quality of the omega 3 fatty acids found in the seals Why is the seal fat rich in unsaturated fatty acids Omega 3 fatty acids can decrease the risk of arrhythmias abnormal heartbeats decrease decrease triglyceride levels slow the growth rate of atherosclerotic plaque lower blood pressure Good sources are seafood such as salmon salmon tuna tuna sardines sardines mackerel or shellfish as well as walnuts flaxseed and canola and soybean oils From American Heart Association website Do you expect cold or warm water fish to be richer with Omega 3 fatty acids Why Both 6 and 3 fatty acids are essential Ex linoleic and linolenic acids 6 derivatives promote inflammation 3 anti inflammatory Healthy ratio of 6 3 1 1 1 4 Typical western diet 10 1 30 1 lower cholesterol in blood The AHA recommends for healthy individuals eat a variety of fish twice a week use heart healthy oils flaxseed canola soybean oils olive and consume flaxseed and walnuts For individuals with heart disease the AHA recommends 1g of EPA eicosapentaenoic acid DHA d docosahexaenoic h i acid id 22 daily d il Read more http www umm edu altmed articles omega 3 000316 htm Membrane lipids Amphiphilic Amphiphilic I I Phosphoglycerides or glycerophospholipids glycerophospholipids Glycerol as a basis Head group substituent defines classes of phosphoglycerides Phosphoester bonds Phosphodiester Ph sph diester bond Phospholipids major membrane components X