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30 Cards in this Set
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- Back
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How do free cholesterol and cholesterol ester molecules differ in structure?
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free cholesterol--> is a 4 ring structure (27 C). Cholesterol esters--> esterification occurs at the OH at C#3
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organ locations for the two enzymes that esterify cholesterol
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LCAT-->occurs on lipoproteins
ACAT-->occurs in cells |
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List sources and uses of cholesterol in humans
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From diet and hepatic synthesis. Is the startingmaterial for: bile acid, vitamin D, steroid hormone synthesis
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The regulated enzyme of choleterol synthesis
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HMG CoA reductase is the regulatated enzyme (rate - limiting step)
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Describe cholesterol synthesis: organ location, starting materials, regulated enzyme
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occurs in the liver, starting materials: acetyl CoA, NADPH, ATP. Regulated enzyme is HMG CoA reductase
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Name the unconjugated primary bile acids
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Chenocholic acid, cholic acid
in hepatocytes |
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Name the conjugated primary bile acids
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Taurocholic acid, glycocholic acid
in hepatocytes |
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Name the secondary bile acids
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deoxycholic acid, lithocholic acid
in hepatocytes |
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Name the starting materials, regulated step, and regulator of bile acid biosynthesis
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Starting material: cholesterol, ATP, NADPH. Controlled step: 7-alpha hydroxycholesterol production from cholesterol. feedback inhibited by high bile salt levels
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Fate of most bile acids
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most bile salts are reabsorbed
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define lipoprotein
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an LDL particle that is covalently bound to an apoprotein (a).
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Name the various lipoproteins
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Chylomicrons, chylomicron remnants, VLDL, IDL, LDL, HDL2, HDL3, lipoprotein (a)
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Two Apoproteins of lipoproteins
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apo CII--> cofactor activator of lipoprotein lipase(LPL)
, apo E--> ligand for binding of several lipoproteins to the LDL receptor, to the LDL receptor protein (LRP), and possibly to a separate apoE receptor |
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Explain the normal bile acid formation and secretion to lipid digestion
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The conjugation of bile salts to taurine or glycine increases bile acid solubility allowing bile salts to act as detergeants
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what are the 4 common conjugated bile salts?
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taurocholic, glycocholic, taurochenocholic, and glycochenocolic acids
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What does apoE and apoCII do?
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apoE--> recognizes hepatc receptors
apoCII--> ativates lipoprotein lipase |
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Diffrentiate between nascent and maure chylomicrons
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Nascent cylomicrons--> form in the intsines ad pickup triglyceides and cholesterol.
Mature chylomicrons--> once in blood, nascent chylmicrons are modified y HDL that tansers apoE and apoCII |
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Fxn of chylomicrons to transport of triglycerides
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From intestine to lymph to adipose cells where (LPL) lipoprotein lipase convets the chylomicron triglycrides to free FAs ad glyceol
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How is lipoprotein lipase activted?
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apoCII (from HDL) activte LPL,
also, insulin increases LPL activity by inducing its synthesis. |
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chylomicron remnants
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are chylmcrons w/o their triglycerides and are sent to the liver where they are broken down into their component molecules
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When and where are VLDLs synthsized?
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Made in the liver when FAs are syntesized in the liver.
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What transports dietary and synthesized triglycerides
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Chylomicons deliver dietary triglycerides
VLDLs are analogous to chylmicrons but they deliver FAs synthesized by the liver |
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VLDLs transport hepatic triglycerides to what organs?
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skeletal muscle and to adipose tissue
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Give the fate of VLDLs once their delivery of triglycerides
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VLDL becomes IDL. Lipoprotein lipase (LPL) breaks the VLDL triglycerides into FAs and glycerol. The FAs go to adipose or skeletal muscle, glycerol goes to liver
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Give the source and 2 fates of IDL
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comes from VLDLs after break down and goes to the liver and degraded or is converted to LDL
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Describe how IDL are converted to LDL
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Core triglycerides are removed from IDL in the liver with hepatic triglyceride lipase (HTGL) raising its density and becoming LDL
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What role does HDL play in making IDL into LDL?
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HDL use LCAT to esterfy cholesterol that is transferred from HDL to IDL as IDL becomes LDL
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indicate the fxn of LDL
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delivers cholesterol to extrhepatic cells
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What are LRP
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LDL-receptor related protein (LRP). In liver, brain, and placetal membrane surfaces. Recognizes a wider range of lipoproteins and may help decrease serum lipoproteins
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indicate if LDL can enter the liver.
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Yes
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