Question 1

Show the reaction that limits the rate of cholesterol synthesis from acetate, indicating the role of any cofactors that participate.

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Question 2

What is the primary genetic defect that leads to familial hypercholesterolemia, and how does it lead to elevated blood cholesterol levels?

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Question 3

Describe briefly the four stages in the pathway from acetyl-CoA to lanosterol.

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Question 4

What is the "cost" of synthesizing palmitate from acetyl-CoA in the cytosol in terms of high-energy molecules consumed?

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Question 5

Show the two different biosynthetic pathways from phosphatidic acid to phosphatidylcholine. You may use shorthand notation for phosphatidic acid, but name any cofactors required in the path and show where they are involved.

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Question 6

Describe the formation of farnesyl pyrophosphate from activated isoprenyl units.

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Question 7

Show the pathway from mevalonate to dimethylallyl pyrophosphate, indicating where any cofactors participate.

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Question 8

Describe the process by which cholesterol esters in the bloodstream enter cells.

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Question 9

The synthetic compound mevinolinic acid, also called lovastatin, is a potent competitive inhibitor of HMG-CoA reductase (hydroxymethylglutaryl-CoA reductase). Predict and explain the effect of this drug on serum cholesterol levels in humans.

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Question 10

Show the pathway from acetyl-CoA to mevalonate, indicating the roles of any cofactors.

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Question 11

Describe (briefly) two classes of genetic defects in humans that could produce an elevated blood serum cholesterol level.

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Question 12

How does the energy cost of each round of fatty acid synthesis compare to each round of energy output from$\beta$ oxidation?

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Question 13

Shown below is a molecule of squalene, which is composed of six isoprene units. Draw lines to indicate the junctions between the six isoprene units.

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Question 14

What are plasma lipoproteins? What is their general role in mammalian metabolism?

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Question 15

Show the structure of isopentenyl pyrophosphate and of dimethylallyl pyrophosphate. Connect with a dotted line the two carbon atoms that will be joined when these two molecules condense to form the 10-carbon intermediate in cholesterol biosynthesis.

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Question 16

Which phospholipase is critical for eicosanoid synthesis and why?

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Question 17

Reduction of the gluconeogenesis intermediates dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (GAP) can generate glycerol-3-phosphate (G3P) as a product. Why does it make sense to use DHAP instead of GAP in G3P formation?

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Question 18

The synthesis of cholesterol begins with the condensation of a four-carbon unit from _____ with the two carbons of acetyl-CoA to form a six-carbon derivative. Give its structure, and circle the atoms that originated in the acetyl-CoA.

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Question 19

When a 10-carbon unit and a 5-carbon unit condense to a 15-carbon intermediate in the pathway to cholesterol, the mechanism of condensation is basically different from that of the condensation of two 15-carbon units to the 30-carbon compound squalene. Describe the two condensations in enough chemical detail to illustrate the difference between them. (You should show relevant structures.)

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Question 20

Describe two basic strategies for activating precursors in the biosynthesis of phospholipids.

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Quiz 21: Lipid Biosynthesis

Show the reaction that limits the rate of cholesterol synthesis from acetate, indicating the role of any cofactors that participate.

What is the primary genetic defect that leads to familial hypercholesterolemia, and how does it lead to elevated blood cholesterol levels?

Describe briefly the four stages in the pathway from acetyl-CoA to lanosterol.

What is the "cost" of synthesizing palmitate from acetyl-CoA in the cytosol in terms of high-energy molecules consumed?

Show the two different biosynthetic pathways from phosphatidic acid to phosphatidylcholine. You may use shorthand notation for phosphatidic acid, but name any cofactors required in the path and show where they are involved.

Describe the formation of farnesyl pyrophosphate from activated isoprenyl units.

Show the pathway from mevalonate to dimethylallyl pyrophosphate, indicating where any cofactors participate.

Describe the process by which cholesterol esters in the bloodstream enter cells.

The synthetic compound mevinolinic acid, also called lovastatin, is a potent competitive inhibitor of HMG-CoA reductase (hydroxymethylglutaryl-CoA reductase). Predict and explain the effect of this drug on serum cholesterol levels in humans.

Show the pathway from acetyl-CoA to mevalonate, indicating the roles of any cofactors.

Describe (briefly) two classes of genetic defects in humans that could produce an elevated blood serum cholesterol level.

How does the energy cost of each round of fatty acid synthesis compare to each round of energy output from $\beta$ oxidation?

Shown below is a molecule of squalene, which is composed of six isoprene units. Draw lines to indicate the junctions between the six isoprene units.

What are plasma lipoproteins? What is their general role in mammalian metabolism?

Show the structure of isopentenyl pyrophosphate and of dimethylallyl pyrophosphate. Connect with a dotted line the two carbon atoms that will be joined when these two molecules condense to form the 10-carbon intermediate in cholesterol biosynthesis.

Which phospholipase is critical for eicosanoid synthesis and why?

Reduction of the gluconeogenesis intermediates dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (GAP) can generate glycerol-3-phosphate (G3P) as a product. Why does it make sense to use DHAP instead of GAP in G3P formation?

The synthesis of cholesterol begins with the condensation of a four-carbon unit from _____ with the two carbons of acetyl-CoA to form a six-carbon derivative. Give its structure, and circle the atoms that originated in the acetyl-CoA.

Describe two basic strategies for activating precursors in the biosynthesis of phospholipids.

Quiz 21: Lipid Biosynthesis

Show the reaction that limits the rate of cholesterol synthesis from acetate, indicating the role of any cofactors that participate.

What is the primary genetic defect that leads to familial hypercholesterolemia, and how does it lead to elevated blood cholesterol levels?

Describe briefly the four stages in the pathway from acetyl-CoA to lanosterol.

What is the "cost" of synthesizing palmitate from acetyl-CoA in the cytosol in terms of high-energy molecules consumed?

Show the two different biosynthetic pathways from phosphatidic acid to phosphatidylcholine. You may use shorthand notation for phosphatidic acid, but name any cofactors required in the path and show where they are involved.

Describe the formation of farnesyl pyrophosphate from activated isoprenyl units.

Show the pathway from mevalonate to dimethylallyl pyrophosphate, indicating where any cofactors participate.

Describe the process by which cholesterol esters in the bloodstream enter cells.

The synthetic compound mevinolinic acid, also called lovastatin, is a potent competitive inhibitor of HMG-CoA reductase (hydroxymethylglutaryl-CoA reductase). Predict and explain the effect of this drug on serum cholesterol levels in humans.

Show the pathway from acetyl-CoA to mevalonate, indicating the roles of any cofactors.

Describe (briefly) two classes of genetic defects in humans that could produce an elevated blood serum cholesterol level.

How does the energy cost of each round of fatty acid synthesis compare to each round of energy output from β\betaβ oxidation?

Shown below is a molecule of squalene, which is composed of six isoprene units. Draw lines to indicate the junctions between the six isoprene units.

What are plasma lipoproteins? What is their general role in mammalian metabolism?

Show the structure of isopentenyl pyrophosphate and of dimethylallyl pyrophosphate. Connect with a dotted line the two carbon atoms that will be joined when these two molecules condense to form the 10-carbon intermediate in cholesterol biosynthesis.

Which phospholipase is critical for eicosanoid synthesis and why?

Reduction of the gluconeogenesis intermediates dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (GAP) can generate glycerol-3-phosphate (G3P) as a product. Why does it make sense to use DHAP instead of GAP in G3P formation?

The synthesis of cholesterol begins with the condensation of a four-carbon unit from _____ with the two carbons of acetyl-CoA to form a six-carbon derivative. Give its structure, and circle the atoms that originated in the acetyl-CoA.

Describe two basic strategies for activating precursors in the biosynthesis of phospholipids.

How does the energy cost of each round of fatty acid synthesis compare to each round of energy output from $\beta$ oxidation?