LIVERINTESTIchyLipoproteinsTypes oflipoproteinsOTHERTISSUE口VLDL(very-low-densitylipoprotein)Particles of TAGs, phospholipids, cholesteryl esters packaged by liverCirculate in blood and donate some of TAGtotissuesBecome smaller and denser and richer in cholesterol as they donate TAGs IDL(intermediate-density lipoproteins)Form as VLDL gives off TAGIntermediate state between VLDL and LDL
Lipoproteins Types of lipoproteins VLDL (very-low-density lipoprotein) • Particles of TAGs, phospholipids, cholesteryl esters packaged by liver • Circulate in blood and donate some of TAG to tissues • Become smaller and denser and richer in cholesterol as they donate TAGs IDL (intermediate-density lipoproteins) • Form as VLDL gives off TAG • Intermediate state between VLDL and LDL
LIVERVLDLLipoproteinsTypes oflipoproteinsINTELDI国LDL(low-densitylipoproteinOTHERForm as more TAG given off from IDL particlesTSSUEHigh levels correlated to atherosclerosis“Bad cholesterol" HDL (high-density lipoproteins)Primary function is to transport excess cholesterol back to liverRemoveexcesscholesterolfromcells“Good cholesterol
Lipoproteins Types of lipoproteins LDL (low-density lipoprotein) • Form as more TAG given off from IDL particles • High levels correlated to atherosclerosis • “Bad cholesterol” HDL (high-density lipoproteins) • Primary function is to transport excess cholesterol back to liver • Remove excess cholesterol from cells • “Good cholesterol
BIOPOLYMERSTriacylglycerolsMONOMERSFattyacidsLipid metabolism in contextNHA3NAD+NAD Triacylglycerols contain fattyNADH-NADH,QH2acids attached to a glycerol2-and3-CarbonINTERMEDIATESbackbonecitric Fatty acids are broken down intophoto-NAD*,Qacidsynthesiscycle2Cand3Cintermediatesthatfeed into the citric acid cycleNADH,QH2-ADPO.oxidativephosphorylationH20NAD+,Q
Lipid metabolism in context Triacylglycerols contain fatty acids attached to a glycerol backbone Fatty acids are broken down into 2C and 3C intermediates that feed into the citric acid cycle
Triacyigycerediacreoupbsipld5Summary of lipid metabolismAcylCeaACYEACMajor pathwaysONADP Fatty acid catabolism (β oxidation)21Saxidotionfemyecidsyrehesi Fatty acid synthesiswclCoAFydroxyacyt-ACJHTNADKNADPHKetogenesis1-KatoacysCoBKtosAC(synthesis of ketone bodies)M Cholesterol synthesis Synthesis of other lipids3HMGCOAketogenesicidAll pathways converge at acetyl-CoAcyceCaonedNADPH
Summary of lipid metabolism Major pathways Fatty acid catabolism (β oxidation) Fatty acid synthesis Ketogenesis (synthesis of ketone bodies) Cholesterol synthesis Synthesis of other lipids All pathways converge at acetyl-CoA
Fattyacid catabolism Degradation of fatty acids is β oxidation Dietary TAGs are the primary source in humans TAGs are hydrolyzed to FA groups by lipases FA in bloodstream bound to albumin(about 50% of protein in bold is albumin)Notwater-solubleCH2CH--CH2O3H20000CH2-CH-CH23RCOlipoproteinOHOHOHC0C0C-0lipaseRRRGlycerolTriacylglycerolFattyacyl groups
Fatty acid catabolism Degradation of fatty acids is β oxidation Dietary TAGs are the primary source in humans TAGs are hydrolyzed to FA groups by lipases FA in bloodstream bound to albumin (about 50% of protein in bold is albumin) Not water-soluble