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Questions

Question 1

What is the irreversible process that commits acetyl-CoA to fatty acid synthesis, and what enzyme catalyzes it?

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Question 2

In the mammalian fatty acid synthase I (FAS I) system, what is the role of the acyl carrier protein (ACP)?

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Question 3

What is the net equation for the synthesis of one molecule of palmitate from 8 molecules of acetyl-CoA?

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Question 4

In nonphotosynthetic eukaryotes, how is acetyl-CoA, the precursor for fatty acid synthesis, transported from the mitochondria to the cytosol?

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Question 5

What is the primary mechanism by which citrate regulates fatty acid synthesis in vertebrates?

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Question 6

How do mammals synthesize the monounsaturated fatty acid oleate, 18:1(delta9)?

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Question 7

Which class of molecules, derived from 20-carbon polyunsaturated fatty acids, are considered short-range signaling molecules that mediate inflammation, pain, and fever?

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Question 8

What is the common metabolic precursor for the synthesis of both triacylglycerols and glycerophospholipids in animal tissues?

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Question 9

How does insulin promote the conversion of carbohydrate to triacylglycerols?

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Question 10

What is the primary role of the triacylglycerol cycle that operates between adipose tissue and the liver, especially during fasting?

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Question 11

What is the main source of glycerol 3-phosphate for triacylglycerol synthesis in adipose tissue, especially during fasting?

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Question 12

In eukaryotic cells, where does the synthesis of cardiolipin and phosphatidylinositol primarily occur?

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Question 13

What is the activated intermediate used for the synthesis of phosphatidylinositol and cardiolipin in eukaryotes?

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Question 14

What are the four main stages of cholesterol biosynthesis from acetyl-CoA?

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Question 15

What is the energetic cost, in terms of ATP molecules, to synthesize one molecule of squalene from acetyl-CoA?

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Question 16

Which enzyme is the major point of regulation in the cholesterol biosynthesis pathway and is the target of statin drugs?

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Question 17

What is the function of low-density lipoprotein (LDL)?

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Question 18

In the context of familial hypercholesterolemia (FH), what is the primary defect that leads to very high blood levels of cholesterol?

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Question 19

What is the primary function of high-density lipoprotein (HDL) in cholesterol transport?

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Question 20

How do sterol regulatory element-binding proteins (SREBPs) regulate cholesterol synthesis in response to low cellular sterol levels?

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Question 21

What is the common intermediate that is condensed to form porphobilinogen in the synthesis of heme?

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Question 22

What is the role of ferrochelatase in heme synthesis?

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Question 23

In the degradation of heme, what is the immediate green-colored precursor to the yellow-colored bilirubin?

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Question 24

What is the function of the enzyme cyclooxygenase (COX), also known as prostaglandin H2 synthase?

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Question 25

What is the biochemical basis for the different physiological roles of the COX-1 and COX-2 isozymes?

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Question 26

What is the primary product of the mammalian fatty acid synthase I (FAS I) system?

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Question 27

In eukaryotes, the synthesis of phosphatidylcholine can occur through the Kennedy pathway. What is the activated intermediate that condenses with diacylglycerol in this pathway?

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Question 28

In sphingolipid synthesis, what are the initial two reactants that condense to form the backbone of sphinganine?

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Question 29

Which of the following molecules serves as the activated donor of the phosphocholine head group in the synthesis of sphingomyelin in animals?

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Question 30

What is the source of the oxygen atom that forms the ether linkage in plasmalogen synthesis?

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Question 31

Which molecule is formed from the head-to-head condensation of two molecules of farnesyl pyrophosphate?

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Question 32

What is the primary role of apolipoprotein C-II (apoC-II)?

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Question 33

The drug rosiglitazone (Avandia) is a thiazolidinedione used to treat type 2 diabetes. What is its mechanism of action related to lipid metabolism?

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Question 34

In the four-step repeating sequence of fatty acid synthesis, what is the source of reducing power for the two reduction steps?

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Question 35

What is the function of the thioesterase (TE) domain of the mammalian fatty acid synthase I?

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Question 36

Mammals cannot synthesize linoleate (18:2) and alpha-linolenate (18:3). Why are these considered essential fatty acids?

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Question 37

What is the mechanism by which aspirin inhibits the synthesis of prostaglandins?

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Question 38

What are the two activated isoprene units that are central to cholesterol formation?

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Question 39

In the four-stage pathway of cholesterol synthesis, the conversion of which linear molecule to a four-ring structure is a key step?

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Question 40

What is the primary carrier of newly synthesized triacylglycerols and cholesterol from the liver to peripheral tissues in the endogenous pathway of lipid transport?

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Question 41

How is the uptake of LDL by peripheral cells primarily mediated?

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Question 42

What is the function of the enzyme lecithin-cholesterol acyl transferase (LCAT)?

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Question 43

How does the transcription factor LXR (Liver X receptor) contribute to cholesterol homeostasis when cellular cholesterol levels are high?

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Question 44

In the condition atherosclerosis, what are foam cells?

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Question 45

What is the final linear precursor that undergoes cyclization to form the steroid nucleus in cholesterol biosynthesis?

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Question 46

Besides cholesterol, what other important biological molecules are derived from isopentenyl pyrophosphate?

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Question 47

What is the initial source of the two-carbon units that are added to a growing fatty acid chain during its synthesis?

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Question 48

What is the function of the genetic disease Niemann-Pick type-C (NPC)?

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Question 49

What is the role of the APOE4 allele in human health?

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Question 50

How many molecules of acetyl-CoA are required to form the six-carbon intermediate, beta-hydroxy-beta-methylglutaryl-CoA (HMG-CoA), in the first stage of cholesterol biosynthesis?

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