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15 Cards in this Set

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What is the chemical structure of Cholesterol?
<img src="http://www.heart-disease-bypass-surgery.com/data/images/cholesterol.gif">
How many carbons are in Cholesterol? and what is contained in the structure?
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
What is the precursor of cholesterol synthesis?
Acetyl CoA
Where does cholesterol synthesis occur and what are the tissues associated with it?
Cytosol
Liver (1 g/day~20-25% of daily production), Intestines, Adrenal glands, Reproductive organs
What is sterol?
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.
The basic a-b-c-d structure of cholesterol rings
Name the starting materials and intermediates in stage 1 cholesterol synthesis.
Acetyl-CoA, Acetoacetyl CoA, beta-hydroxy-Beta-methyl-glutaryl CoA
Which stage in Cholesterol synthesis is the committed, rate limiting step in cholesterol formation?
Stage 1
What enzyme catalyzes the reduction to mevalonate in stage 1 of Cholesterol Synthesis?
HMG-CoA reductase
Name the starting material and intermediates in stage 2 cholesterol synthesis.
ATP, Mevalonate, 5-pyrophosphate mevalonate, 3-phospho 5-pyrophosphate mevalonate, -isopentenyl pyrophosphate, dimethylallyl pyrophosphate
Name the starting material and intermediates in stage 3 cholesterol synthesis.
Dimethylallyl pyrophosphate + -isopentyl pyrophosphate= geranyl pyrophosphate = farnesyl pyrophosphate = squalene
Name the starting material and intermediates in stage 4 cholesterol synthesis.
Squalene, squalene 2,3 -epoxide, Lanosterol, cholesterol
What are the reducing agents needed for cholesterol synthesis?
2NADPH for HMG-CoA reductase
NADPH for squalene monooxygenase
Describe how the fate of cytosolic HMG-CoA differs from that of mitochrondrial HMG-CoA.
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
What does the carbon skeleton of an isopene unit look like?
<img src="http://upload.wikimedia.org/wikipedia/en/4/4e/Isoprene_structure.png">
Describe the control of the activity or amount of HMG-CoA reductase.
In the liver, inhibited by bile salts and induced when blood insulin levels are elevated and others