Term
| What are the five types of lipoproteins? |
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Definition
| Chylomicrons, very-low density lipoproteins, low density lipoproteins, intermediate density lipoproteins and high density lipoproteins |
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Term
| True or false: Lipoprotein lipase (LPL) is an intracellular enzyme that catalyzes the degradation of VLDL and chylomicrons to their constituent parts, releasing monoacylglycerols and fatty acids into skeletal muscle and adipose tissue. |
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Definition
| False, it is extracellular but the rest is correct |
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Term
| These apolipoproteins activate LPL |
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Definition
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Term
| The LDL receptor binds what two apoproteins on the LDL molecule? |
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Definition
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Term
| Definition: A general mechanism wherein cells take up large molecules through a corresponding, specific receptor |
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Definition
| Receptor Mediated Endocytosis |
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Term
| LDLRs cluster around these structures, which enclose ingested LDL and fuse with a lysosome for further degradation. |
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Definition
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Term
| Cholesterol delivered by VLDL to the tissues is esterified by this enzyme, associated with HDL |
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Definition
| lecithin-cholesterol acyltransferase, LCAT |
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Term
| The liver disposes of excess cholesterol by incorporating it into what digestive substance? |
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Definition
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Term
| What two ways does the body prevent excess intracellular cholesterol accumulation? |
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Definition
| Negative feedback of increased cholesterol on cholesterol biosynthesis in the liver, and decreased expression of the LDLR on cell surfaces |
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Term
| LDL contains only this apoprotein, which is recognized by the LDLR in addition to apoE |
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Definition
| apoB-100, IDL has apoE and apoB-100 but not apoC-II |
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Term
| Not to be confused with scavenger receptors, HDL scavenges cholesterol from cells and brings it back to the liver by way of this enzyme, activate by this apoprotein |
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Definition
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Term
| What percent of VLDL is taken up by the liver through LDLR? |
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Definition
| 50%, other half is hydrolyzed to LDL by LPL |
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Term
| True or false: HDL is taken up by the liver in a manner similar to VLDL, receptor-mediated endocytosis |
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Definition
| False, HDL binds to the SR-BI receptor on hepatocytes and transfers its cholesterol esters before disassociating and returning to circulation |
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Term
| True or false: All of the LDLR are found in the liver |
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Definition
| False, 70% in liver but other tissues (skeletal muscle, adipose tissue) have LDLR as well |
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Term
| What percent of total body cholesterol is circulated in the plasma? |
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Definition
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Term
| True or false: VLDL and LDL are rich in triacylglycerols, while HDL is rich in cholesteryl esters |
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Definition
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Term
| Circulating macrophages, while low in LDLR, contain many of these types of receptors, which can assist in the phagocytosis of oxidized-LDL |
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Definition
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Term
| These substances, found in blueberries and citrus fruits, prevent scavenger receptor uptake of LDL in the plasma by protecting the N-terminus |
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Definition
| Anti-oxidants, only oxidized LDL can by taken up by scavenger receptors on macrophages, they lose their protection while in atheromas in SM of arteries |
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Term
| True or false: Familial hypercholesteremia, an autosomal dominant disease, results from mutations in the LDLR |
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Definition
| True, homozygotes have severe cholesteremia and can have myocardial infarctions by the age of 5 |
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Term
| 5 different mutations on the LDLR gene can cause familial hypercholesteremia, what are they? |
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Definition
| Synthesis disorders, no LDLR at all. Transport disorders, LDLR are made but aren't transported to the golgi complex. Binding, LDLR fuse with cell membrane but can't bind apoE or apoB-100. Pit formation, LDLR bind apoproteins but can't cluster in coated pits. Endosome fusion, clathrin coated pits are formed but they don't bind with the endosome. |
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Term
| This enzyme, the inhibition target of statin drugs, is key in synthesizing cholesterol endogenously, it is inhibited by increased intracellular cholesterol. |
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Definition
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