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15 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What is the chemical structure of Cholesterol?
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<img src="http://www.heart-disease-bypass-surgery.com/data/images/cholesterol.gif">
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How many carbons are in Cholesterol? and what is contained in the structure?
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27 carbons
C3 hydroxyl group C5 & C6 double bond eight membered hydrocarbon chain attached to C17 in the D ring C19 methyl group C13 methyl group |
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What is the precursor of cholesterol synthesis?
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Acetyl CoA
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Where does cholesterol synthesis occur and what are the tissues associated with it?
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Cytosol
Liver (1 g/day~20-25% of daily production), Intestines, Adrenal glands, Reproductive organs |
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What is sterol?
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Steroid alcohol: All sterols are biosynthetically derived either from the sterol lanosterol (animals or fungi) or the sterol cycloartenol (plants). Both sterols are derived from the cyclization of the triterpene squalene.
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The basic a-b-c-d structure of cholesterol rings
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Name the starting materials and intermediates in stage 1 cholesterol synthesis.
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Acetyl-CoA, Acetoacetyl CoA, beta-hydroxy-Beta-methyl-glutaryl CoA
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Which stage in Cholesterol synthesis is the committed, rate limiting step in cholesterol formation?
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Stage 1
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What enzyme catalyzes the reduction to mevalonate in stage 1 of Cholesterol Synthesis?
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HMG-CoA reductase
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Name the starting material and intermediates in stage 2 cholesterol synthesis.
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ATP, Mevalonate, 5-pyrophosphate mevalonate, 3-phospho 5-pyrophosphate mevalonate, -isopentenyl pyrophosphate, dimethylallyl pyrophosphate
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Name the starting material and intermediates in stage 3 cholesterol synthesis.
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Dimethylallyl pyrophosphate + -isopentyl pyrophosphate= geranyl pyrophosphate = farnesyl pyrophosphate = squalene
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Name the starting material and intermediates in stage 4 cholesterol synthesis.
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Squalene, squalene 2,3 -epoxide, Lanosterol, cholesterol
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What are the reducing agents needed for cholesterol synthesis?
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2NADPH for HMG-CoA reductase
NADPH for squalene monooxygenase |
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Describe how the fate of cytosolic HMG-CoA differs from that of mitochrondrial HMG-CoA.
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Mitchochondrial HMG CoA is the precursor of Acetoacetate and Acetyl CoA in Keto body synthesis
HMG-CoA in cholesterol synthesis is reduced at ER membrane |
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What does the carbon skeleton of an isopene unit look like?
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<img src="http://upload.wikimedia.org/wikipedia/en/4/4e/Isoprene_structure.png">
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Describe the control of the activity or amount of HMG-CoA reductase.
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In the liver, inhibited by bile salts and induced when blood insulin levels are elevated and others
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