Chapter 20
Which of the following is TRUE regarding the enzyme acetyl-CoA carboxylase?I. It catalyzes the first committed step in fatty acid oxidation.II. It requires S-adenosylmethionine.III. It produces malonyl CoA.IV. It uses acetyl CoA. I, II, III, IV I only I, III, IV III, IV III only
III, IV
Which of the following has NO EFFECT on the activity of acetyl-CoA carboxylase? Palmitate Citrate Covalent modification Malonyl-CoA Glucagon
Malonyl-CoA (Acetyl-CoA carboxylase is not inhibited by the product of the reaction it catalyzes.)
The complete combustion of palmitate and glucose yields 9781 kJ · mol-1 and 2850 kJ · mol-1 of free energy, respectively. Palmitate oxidation produces _______ ATP and glucose catabolism produces ______ ATP. The standard free energy of ATP synthesis from ADP + Pi is ______ kJ · mol-1. Palmitate catabolism therefore has an efficiency of ______ %. Likewise, glucose catabolism has an efficiency of ______ %. Thus, the two processes have _________ overall efficiency.
106; 32; 30.5 ; 33 ; 34; very nearly the same
Which of the following enzymes is NOT involved in the tricarboxylate transport system? A. citrate synthase B. ATP citrate lyase C. malate dehydrogenase D. malic enzyme E. All are involved in the transport of acetyl-CoA into the cytosol
E. All are involved in the transport of acetyl-CoA into the cytosol
Which of the following plays NO role in the synthesis of fatty acids in the liver? A. Carnitine. B. CO2 (HCO3-). C. Glucose. D. Amino acids. E. Citrate.
A. Carnitine.
______, a condition in which acetoacetate production exceeds it metabolism and results in a sweet breath odor due to nonenzymatic ___ of acetoacetate to _____. A. ketosis; decarboxylation; acetone B. ketosis; carboxylation; hydroxylbutyrate C. glyceroneogenesis; decarboxylation; hydroxylbutyrate D. ketosis; decarboxylation; hydroxylbutyrate E. glyceroneogenesis; decarboxylation; acetone
A. ketosis; decarboxylation; acetone
An important structural lipid found in nerve cell membranes, ______, is a type of ______. A. sphingomyelin, phospholipid B. phosphatidylcholine, phospholipid C. palmitate, glycerophospholipid D. glucagon, hormone E. none of the above
A. sphingomyelin, phospholipid
In which of the following ways are fatty acid synthesis and β-oxidation similar? A. The intracellular location of the enzymes involved. B. Their requirement for high-energy phosphates. C. Their use of a repetitive series of redox and addition/elimination reactions. D. Their use of acyl-carrier protein. E. Their use of the same electron carriers.
C. Their use of a repetitive series of redox and addition/elimination reactions.
During starvation, what is the MAJOR fuel source for the production of ketone bodies? A. Glycogen stored in the liver. B. Fats absorbed from the intestinal tract. C. Amino acids from skeletal muscle. D. Fats stored in adipose tissue.
D. Fats stored in adipose tissue.
Which of the following does NOT play a role in determining the rate of cholesterol synthesis in humans? A. Glucose B. Insulin C. Cholesterol D. Glycogen
D. Glycogen
The rate of breakdown of TAGs in adipocytes is determined by the activity of which of the following enzymes? A. Lipoprotein lipase B. Pancreatic lipase C. Fatty acyl lipase D. Hormone-sensitive lipase
D. Hormone-sensitive lipase
Which of the following statements about lipolysis in adipocytes is TRUE? A. Its rate is increased when the rate-limiting enzyme is dephosphorylated. B. Its rate is determined by the supply of substrate. C. It results in the release of triacylglycerols into the blood stream. D. It is increased in response to a glucagon signal.
D. It is increased in response to a glucagon signal.
Which of the following statements about lipases is/are TRUE? 1 Pancreatic lipases break down TAGs in the intestine. 2 Hormone-sensitive lipase is located primarily in the liver. 3 Lipoprotein lipase is located in blood vessel walls. 4 Lipoprotein lipase helps deliver cholesterol in peripheral tissues. 1, 3 and 4 3 and 4 2 and 4 1 and 3 1, 2 and 3
1 and 3
The inner mitochondrial membrane contains a specific transporter protein for which of the following substances1 pyruvate2 fatty acyl-CoA3 PEP4 acetyl-CoA5 Pi 1 and 5 1, 2 and 5 1, 2, and 4 1, 3, 5 1, 2, 3, 4, and 5
1, 3, 5
What is the net production of ATP from complete catabolism of the following fatty acid to CO2 and H2O? 51 - 90 151 + 91 - 120 121 - 150 < 50
51 - 90
If 1 mol of a fatty acyl-CoA containing 20 carbon atoms undergoes three rounds of β-oxidation, how many mol of ATP are produced from the complete aerobic catabolism of the products of these three rounds? Assume that re-oxidation of NADH via the electron transport chain yields the equivalent of 3 ATP, and that re-oxidation of FADH2 yields 2 ATP. (The remaining acyl-CoA is NOT catabolized further.) 165 ATP 44 ATP 49 ATP 46 ATP 51 ATP
51 ATP
How many molecules of water are produced by the electron transport chain during the complete aerobic oxidation of 1 molecule of stearate (C18:0) to CO2 and water? 146 H2O 52 H2O 54 H2O 148 H2O 50 H2O
52 H2O
If the fatty acid 12:1Δ7 is completely catabolized to CO2 and H2O, what would be the net yield of ATP? (Assume that re-oxidation of NADH via the electron transport chain yields the equivalent of 3 ATP, and that re-oxidation of FADH2 yields 2 ATP.) 92 ATP 94 ATP 97 ATP 93 ATP 95 ATP
93 ATP
If the 14-carbon saturated fatty acid myristoyl-CoA is oxidized completely to carbon dioxide and water (via the β-oxidation pathway, the citric acid cycle and oxidative phosphorylation), what is the yield of ATP per molecule of myristoyl-CoA? (Assume that re-oxidation of NADH via the electron transport chain yields the equivalent of 2.5 ATP, and that re-oxidation of FADH2 yields 1.5 ATP.) 92 ATP 94 ATP 98 ATP 100 ATP
94 ATP
For the following process, indicate whether it is activated (A) or inhibited (B) during FASTING.Lipolysis in adipocytes. (A/B) B A
A
What are the major products produced by β-oxidation of the acyl-CoA heptadecanoyl-CoA (17:0)? A. 7 Acetyl-CoA, 7 FADH2, 7 NADH, 1 Propionyl-CoA B. 8 Acetyl-CoA, 7 FADH2, 7 NADH, 1 Propionyl-CoA C. 8 Acetyl-CoA, 8 FADH2, 8 NADH, 1 Propionyl-CoA D. 8 Acetyl-CoA, 7 FADH2, 7 NADH, 1 Succinyl-CoA E. 7 Acetyl-CoA, 7 FADH2, 7 NADH, 1 Succinyl-CoA
A. 7 Acetyl-CoA, 7 FADH2, 7 NADH, 1 Propionyl-CoA
Which statement concerning phospholipid synthesis is true? A. Addition of polar "head groups" to diacylglycerol usually involves CDP derivatives. B. Addition of polar "head groups" to diacylglycerol usually involves UDP adducts. C. Addition of fatty acyl "tails" to glycerol usually involves CDP adducts. D. Addition of fatty acyl "tails" to glycerol usually involves UDP adducts. E. None of the above is true.
A. Addition of polar "head groups" to diacylglycerol usually involves CDP derivatives.
An enzyme that is inhibited by the statin group of drugs (e.g. Lipitor®) is A. HMG CoA reductase. B. desaturase. C. glycerol kinase. D. hormone sensitive lipase. E. phospholipase A2.
A. HMG CoA reductase.
Which of the following statements about lipolysis in adipocytes is FALSE? A. Its rate is determined by substrate supply. B. It results in the release of fatty acids into the blood stream. C. It is activated in response to phosphorylation of the rate-limiting enzyme. D. It is increased in response to a glucagon signal.
A. Its rate is determined by substrate supply. (This statement is FALSE. Lipolysis (hormone-sensitive lipase) is regulated by hormone-signalling mechanisms and is not affected by the levels of TAGs in adipocytes.)
In the following equation, which substance is being oxidized? L-beta-hydroxy-acyl-CoA + NAD+ -ketoacyl-CoA + NADH + H+ A. L-beta-hydroxy-acyl-CoA B. NAD+ C. NADH D. beta-ketoacyl-CoA
A. L-beta-hydroxy-acyl-CoA
Which of the following terms is used to describe the breakdown of triacylglycerols into free fatty acids and glycerol? A. Lipolysis B. Lipogenesis C. Beta oxidation Both A and B are correct. Both A and C are correct.
A. Lipolysis
Where are the two major sites for fatty acid catabolism in the body? A. Liver and skeletal muscle. B. Liver and adipose tissue. C. Liver and cardiac muscle. D. Skeletal muscle and adipose tissue.
A. Liver and skeletal muscle.
In which cellular compartment are ketone bodies synthesized? A. Mitochondrial matrix. B. Inner mitochondrial membrane. C. Cytosol. D. Mitochondrial intermembrane space.
A. Mitochondrial matrix.
Which of the following statements about phosphatidate is correct? A. Phosphatidic acid can be derived from dihydroxyacetone phosphate. B. Phosphatidate can be formed by two acylations of glycerol. C. Phosphatidate is converted to triacylglycerol by phosphatidic acid phosphatase. D. Phosphatidate is an intermediate of cholesterol biosynthesis.
A. Phosphatidic acid can be derived from dihydroxyacetone phosphate.
Which of the following is an important physiological role of bile salts? A. They assist in the digestion of lipids. B. They assist in the excretion of phospholipids. C. They assist in the excretion of proteins. D. They assist in the digestion of lipoproteins.
A. They assist in the digestion of lipids.
Which single precursor provides all the carbon atoms in the biosynthesis of cholesterol? A. acetyl-CoA B. choline C. acetoacetate D. malonyl-CoA
A. acetyl-CoA
PGH2 is synthesized from ______ and triggers pain and ________. A. arachidonate; inflammation B. NSAIDS; COX-1 C. steroids; fever D. cardiolipins; foam cell development E. salicylic acid; foam cell development
A. arachidonate; inflammation
In which cellular compartment does the following reaction take place? HMG-CoA + 2 NADPH → mevalonate + 2 NADP + + Acetyl-CoA A. cytosol of liver cells B. mitochondria of liver cells C. cells in the intestinal lumen D. lysosomal fluid E. all of the above
A. cytosol of liver cells
The activity of lipases is controlled in part by a process known as ____ which functions effectively due to the ____ where lipases are active. A. interfacial activation; lipid-water interface B. lipase activation; lipid-water interface C. lipase activation; bile salt-water interface D. micelle activation; water-salt interface E. none of the above
A. interfacial activation; lipid-water interface
For the following enzyme, indicate whether it is activated (A) or inhibited (B) during FASTING.Acetyl-CoA carboxylase in the liver. (A/B) B A
B
Which of the following sets of molecules is required prior to the beta-oxidation of a fatty acid? A. ATP, carnitine, and biotin. B. ATP, carnitine, and coenzyme A. C. ATP, elongase and coenzyme A. D. ATP, citrate and coenzyme A.
B. ATP, carnitine, and coenzyme A.
In an individual fed a balanced diet, which of the following does NOT contribute to the synthesis of fatty acids and triacylglycerols (TAGs) in the liver? A. CO2 (HCO3-). B. Acyl-carnitine. C. Carbon skeletons derived from amino acids. D. Dihydroxyacetone phosphate. E. Citrate.
B. Acyl-carnitine.
How will the carbon atoms from an odd numbered fatty acid enter the citric acid cycle? A. As acetyl-CoA and propionyl-CoA. B. As acetyl-CoA and succinyl-CoA. C. As acetyl-CoA and malate. D. As acetyl-CoA and citrate.
B. As acetyl-CoA and succinyl-CoA. (Oxidation of odd-chain fatty acids yields acetyl-CoA and propionyl-CoA. Acetyl-CoA can enter the citric acid cycle directly, whereas propionyl-CoA must be converted to succinyl-CoA for entry into the citric acid cycle.)
Some athletes believe that dietary carnitine supplements will enhance their ability to perform aerobic exercise. Which of the following statements best describes the "scientific" basis of this belief? A. Carnitine activates carnitine-acyl transferase-1 (CAT-1) thereby increasing the rate of transport of fatty acids into the mitochondrial matrix. B. Carnitine is required in the transport of fatty acids into the mitochondrial matrix, and so increasing the amount of carnitine will increase the rate of transport. C. Carnitine levels in the cytoplasm are reduced when large amounts of fatty-acyl carnitine are transported into the mitochondrial matrix. D. Carnitine enhances the activation of fatty acids to fatty acyl-CoA, thereby increasing the rate of their transport into the mitochondrial matrix.
B. Carnitine is required in the transport of fatty acids into the mitochondrial matrix, and so increasing the amount of carnitine will increase the rate of transport.
Which enzyme catalyses the key regulatory step of cholesterol synthesis? A. phenyltransferase B. HMG-CoA reductase C. mevalonate-5-phosphotransferase D. HMG-CoA synthase E. β -ketothiolase
B. HMG-CoA reductase
Under which one of the following conditions does the biosynthesis of fatty acids in the liver mainly occur? A. After ingestion of excess triacylglycerols. B. High carbohydrate intake. C. Low carbohydrate intake. D. High cholesterol intake. E. None of the above.
B. High carbohydrate intake. (Glucose is oxidized to form acetyl-CoA, which is the starting material in fatty acid synthesis.)
What role does serum albumin play in fat metabolism? A. It is not involved in fat metabolism in any way. B. It acts as a carrier for free fatty acids in the bloodstream. C. It is a component of lipoproteins. D. It acts as a carrier for the lipoprotein lipase that is responsible for the release of TAGs from VLDL particles.
B. It acts as a carrier for free fatty acids in the bloodstream.
Which of the following statements most accurately describes the role of malonyl-CoA in fatty acid synthesis? A. It is an inhibitor of CAT 1, and thus an activator of fatty acid synthesis. B. It is a temporary "store" of free energy which enables the formation of a new carbon-carbon bond in the growing fatty acyl-chain. C. It regulates acetyl-CoA carboxylase activity via product inhibition, and thus regulates the rate of fatty acid synthesis. D. It is a "high-energy" carrier molecule for CO2, which enables the CO2 to be incorporated in the growing fatty acyl-chain.
B. It is a temporary "store" of free energy which enables the formation of a new carbon-carbon bond in the growing fatty acyl-chain.
In adipocytes, why does the synthesis of triacylglycerols require an external supply of glucose? A. The synthesis of triacylglycerols requires glycerol, which is derived from glucose. B. The synthesis of triacylglycerols requires glycerol 3-phosphate, which is derived from glucose. C. Glucose is required for the production of acetyl-CoA, which is necessary for the synthesis of fatty acids. D. Glucose is required for the anaerobic production of ATP.
B. The synthesis of triacylglycerols requires glycerol 3-phosphate, which is derived from glucose.
How are ketone bodies transported in the bloodstream? A. acetoacetyl-CoA B. beta-hydroxybutyrate C. beta-hydroxybutyryl-CoA D. lactate E. acetone
B. beta-hydroxybutyrate
Which of the following would result in a net increase in uptake of LDL by the liver? A. increased availability of LDL receptors B. high levels of cholesterol synthesis C. increased availability of clathrin triskelions D. all of the above E. none of the above
B. high levels of cholesterol synthesis
Which of the following would result in a net increase in uptake of LDL by the liver? A. increased availability of LDL receptors B. high levels of cholesterol synthesis C. increased availability of clathrin triskelions D. all of the above E. none of the above
B. high levels of cholesterol synthesis
The major site of formation of acetoacetate from fatty acids is: A. kidney B. liver C. intestinal mucosa D. muscle E. adipose tissue
B. liver
What is the final product of fatty acid synthesis? A. palmitoyl-CoA B. palmitate C. butyryl-CoA D. acetyl-CoA
B. palmitate
Pain and inflammation are triggered by ___ which are synthesized by an enzyme inhibited by ____. A. prostaglandins; COX-1 B. prostaglandins; aspirin C. cyclooxygen; NSAIDS D. analgesics; statins E. cardiolipins; aspirin
B. prostaglandins; aspirin
Which of the following vitamins is part of the prosthetic group 5-deoxyadenosylcobalamin? B1 B2 B6 B12 none of the above
B12
Digestion of triacylglycerols is aided by the cholesterol derivatives synthesized by the liver known as: bile acids. lipoproteins. lanosterols. chylomicrons. colipases.
Bile acids
Which carbons in fat, if any, can be converted to glucose? A. None. B. Carbons from the glycerol backbone. C. Carbons from the glycerol backbone and certain carbons from odd chain fatty acids. D. Certain carbons from odd chain fatty acids.
C. Carbons from the glycerol backbone and certain carbons from odd chain fatty acids.
After 3 rounds of β-oxidation, a fatty acyl-CoA intermediate is produced which is designated 12:2Δ3,6. At this point in the process (production of a fatty acyl-CoA intermediate designated 12:2Δ3,6), which of the following is TRUE of the next enzyme-catalyzed reaction? A. It produces NADH. B. It produces FADH2. C. It is an isomerization. D. It is a hydration.
C. It is an isomerization. (Enoyl-CoA isomerase converts the cis- Δ3 (cis- β , γ ) double bond to the trans- Δ2 form which is the normal substrate for enoyl-CoA hydratase.)
Which of the following statements about ketone bodies is FALSE? A. The production of excess ketone bodies can cause metabolic acidosis. B. Ketone bodies are produced under metabolic conditions that are also associated with loss of muscle mass. C. Ketone bodies are produced by the liver when fatty acid supplies are limited. D. Ketone bodies can enter the citric acid cycle as acetyl-CoA. E. The production of ketone bodies increases when blood glucagon levels are high.
C. Ketone bodies are produced by the liver when fatty acid supplies are limited. (This statement is FALSE. Ketone bodies are produced by the liver when fat breakdown predominates and fatty acids are plentiful.)
Which of the following correctly identifies the four reactions of -oxidation and their sequence? A. Dehydration, oxidation, dehydration, thiolysis. B. Oxidation, dehydration, oxidation, thiolysis. C. Oxidation, hydration, oxidation, thiolysis. D. Reduction, hydration, reduction, thiolysis. E. Decarboxylation, dehydration, dehydration, thiolysis.
C. Oxidation, hydration, oxidation, thiolysis.
Which of the following affects the rate of -oxidation? A. The transport of free fatty acids into the matrix. B. The concentration of citrate. C. The rate of electron transport. D. Fructose-2,6-bisphosphate.
C. The rate of electron transport. ("Energy demand" affects the rate of beta-oxidation significantly. When energy demands in the cell are high, the electron transport chain re-oxidizes NADH and FADH2 generating NAD+ and FAD. High levels of NAD+ and FAD enhance the rate of beta-oxidation.)
Which one of the following statements about acetoacetate and 3-hydroxybutyrate is FALSE? A. They require acetyl-CoA for their synthesis. B. They are synthesized in liver mitochondria. C. They may be regarded as water-soluble, transportable forms of citrate in the blood. D. They are fuels for brain and skeletal muscle. E. They give rise to acetone.
C. They may be regarded as water-soluble, transportable forms of citrate in the blood. (This statement is FALSE. Ketone bodies are small, water-soluble, and easily transportable forms of acetate in the blood.)
Which of the following components would be condensed to form acetoacetate? A. malonyl-CoA and acyl-CoA B. acetone and betahydroxybutyrate C. acetyl CoA and acetyl-CoA D. DHAP and glycerol-3-phosphate E. HMG-CoA and acyl-CoA
C. acetyl CoA and acetyl-CoA
Which of the following lipoprotein particles delivers TAGs and cholesterol to target tissues from the intestine (GI tract)? VLDL HDL CM LDL
CM
Which of the following lipoprotein particles has the greatest relative content (percent weight) of TAGs? VLDL HDL CM LDL
CM
The mitochondria of brown adipose tissue contain an additional protein called the "uncoupling protein", which is an H+ ion channel that spans the inner mitochondrial membrane. Which one of the following would result when the uncoupling protein is active? A. No change in the amount of ATP produced per fatty acid catabolized. B. An increase in the storage of triacylglycoerols in the brown adipocytes. C. A decrease in the flux of -oxidation in the matrix. D. A significant increase in heat. E. A decrease in the overall consumption of oxygen.
D. A significant increase in heat. (When active, the uncoupling protein dissipates the H+ ion concentration gradient established across the inner mitochondrial membrane by electron transport. This is an uncoupling of oxidative phosphorylation which would lead to the production of heat.)
Why does the catabolism of fat produce more energy than an equivalent mass of carbohydrate? A. Carbohydrate catabolism involves substrate-level phosphorylation. B. Fat catabolism leads to the formation of thioesters. C. Carbohydrate is catabolized anaerobically. D. Fat catabolism produces more reduced cofactors gram per gram.
D. Fat catabolism produces more reduced cofactors gram per gram.
Fat is a more efficient store of energy than carbohydrate. Which of the following is NOT a factor in this? A. Fatty acids are more highly reduced than carbohydrates. B. Per gram, fatty acids contain twice as many calories as glucose. C. Carbohydrates are polar, hydrophilic molecules. D. Fat is catabolized only aerobically; carbohydrate can be catabolized anaerobically.
D. Fat is catabolized only aerobically; carbohydrate can be catabolized anaerobically. (This statement is FALSE. As written, it does not address why fat is a more efficient store of energy than carbohydrates (glucose).)
Which of the following lipoprotein particles is converted into LDL via the action of lipoprotein lipase? HDL VLDL CM
VLDL
Which of the following statements about peroxisomes is FALSE? A. oxidation in peroxisomes can shorten very long fatty acids. B. Mammalian peroxisomes can synthesize some lipids, including bile salts. C. In plants, peroxisomes and glyoxysomes serve as the site of oxidation. D. Long chain fatty acids are transported into the peroxisome via a carnitine carrier protein where they are activated for oxidation. E. beta oxidation in peroxisomes varies slightly from the mitochondrial process.
D. Long chain fatty acids are transported into the peroxisome via a carnitine carrier protein where they are activated for oxidation.
Which of the following statements about malonyl-CoA is FALSE? A. Malonyl-CoA is a "temporary store" of free energy or a high-energy intermediate. B. Malonyl-CoA is an inhibitor of CAT 1. C. Malonyl-CoA is produced in a carboxylation reaction. D. Malonyl-CoA is an intermediate of cholesterol synthesis.
D. Malonyl-CoA is an intermediate of cholesterol synthesis. (Malonyl-CoA is an intermediate in fatty acid synthesis. Mevalonate, a similar sounding molecule, is an intermediate in cholesterol biosynthesis.)
Which of the following is NOT true of the rate-limiting reaction in fatty acid synthesis? A. This reaction is similar to the reaction catalyzed by pyruvate carboxylase. B. The reaction requires CO2 (or HCO3-). C. The reaction requires one mole of ATP per mole of acetyl-CoA. D. The enzyme that catalyzes this reaction is inhibited by citrate.
D. The enzyme that catalyzes this reaction is inhibited by citrate. (Acetyl-CoA carboxylase is activated by citrate. This makes metabolic sense as citrate transports mitochondrial acetyl-CoA into the cytosol for use in fatty acid synthesis.)
Which of the following is NOT true of the rate-limiting reaction in fatty acid synthesis? A. The reaction requires CO2 (or HCO3-). B. The reaction requires one mole of ATP per mole of acetyl-CoA. C. The reaction is inhibited by palmitate. D. The reaction is a reduction reaction, which bypasses an irreversible reaction in β-oxidation.
D. The reaction is a reduction reaction, which bypasses an irreversible reaction in β-oxidation. ( The rate-limiting step in fatty acid synthesis is a carboxylation reaction catalyzed by acetyl-CoA carboxylase. As beta-oxidation and fatty acid synthesis are independent pathways this reaction does not bypass an irreversible reaction in the beta-oxidation pathway.)
Which of the following is NOT a part of receptor-mediated endocytosis of LDL? A. Apolipoprotein B-100 is hydrolyzed to amino acids in the lysosome. B. The low pH of the endosome causes LDL to dissociate from its receptor. C. LDL receptors are recycled to the plasma membrane. D. The α-helices of apolipoprotein A-I float on the surface of the lipoprotein.
D. The α-helices of apolipoprotein A-I float on the surface of the lipoprotein.
Which of the following best describes arachidonic acid? A. a 20-carbon isoprene-based intermediate of cholesterol synthesis B. a 20-carbon fatty acid essential for cholesterol synthesis C. a 20-carbon isoprene-based compound used for synthesis of prostaglandins D. a 20-carbon fatty acid used for synthesis of prostaglandins E. a 2-carbon compound that functions in conjunction with a fatty acid carrier protein for transport of primed fatty acids
D. a 20-carbon fatty acid used for synthesis of prostaglandins
Which of the following drugs acts by acetylating a serine residue preventing adequate enzyme activity? A. acetaminophen B. ibuprofen C. Vioxx® D. aspirin E. Celebrex®
D. aspirin
Which of the following diets would most likely promote the formation of ketone bodies? A. high simple carbohydrates, low fat B. high complex carbohydrates, high fructose C. high fructose; high whole grain carbohydrates D. high fat, high protein, low carbohydrate E. low fat, high protein, high complex carbohydrates
D. high fat, high protein, low carbohydrate
Which of the following compounds is produced by the multistep cyclization of squalene? A. isoprene B. fanesyl pyrophosphate C. geranyl pyrophosphate D. lanosterol E. isopentyl pyrophosphate
D. lanosterol
In which location listed below does the following reaction take place? HMG-CoA → acetoacetate + Acetyl-CoA A. cytosol of cardiomyocytes B. mitochondria of cardiomyocytes C. cytosol of liver cells D. mitochondria of liver cells E. all of the above
D. mitochondria of liver cells
The glycerol backbone of triacylglycerols is catabolized to ________ .
Dihydroxyacetone phosphate
Triacylglycerols are synthesized by ____ during times of starvation via a process known as ____.
Dihydroxyacetone phosphate; glyceroneogenesis
Complete the following sentence. The catabolism of unsaturated fatty acids, as compared to saturated fatty acids, results in: A. Less ATP synthesis because fewer acetyl-CoA molecules are produced. B. More ATP synthesis since they are higher-energy molecules. C. More ATP synthesis because more reduced cofactors are produced. D. More ATP synthesis because one of the enzymes required is an isomerase. E. Less ATP synthesis because they are more oxidized.
E. Less ATP synthesis because they are more oxidized.
Individuals with significantly reduced levels of carnitine in muscle cells suffer from weakness, even during moderate exercise. This is because: A. They need to inject insulin. B. Fat stores in adipocytes are continuously depleted. C. Carnitine is an allosteric effector of acetyl-CoA carboxylase. D. Electron transport becomes uncoupled from oxidative phosphorylation. E. None of these reasons.
E. None of these reasons.
What is the rate-limiting step in fatty acid synthesis? A. The transport of citrate out of the mitochondrial matrix. B. The production of acetyl-CoA and oxaloacetate from citrate. C. The formation of malonyl-CoA from malonate and coenzyme A. D. The formation of acetyl-CoA. E. The carboxylation of acetyl-CoA.
E. The carboxylation of acetyl-CoA.
Which of the following is the starting metabolite in ketone body biosynthesis? A. acetyl CoA and malonyl CoA B. propionlyl CoA C. acetyl CoA and propionyl CoA D. malonyl CoA E. acetyl CoA
E. acetyl CoA
Which of the following enzymes is NOT activated by insulin? A. acetyl-CoA carboxylase B. HMG-CoA reductase C. glycogen synthase D. PFK-2 E. hormone sensitive lipase
E. hormone sensitive lipase (Hormone sensitive lipase is activated by glucagon.)
Which of the following is the source of the two carbon fragments in fatty acids biosynthesis? A. palmitic acid B. ceramides C. acetyl CoA D. propionyl CoA E. malonyl CoA
E. malonyl CoA
Cholesterol and other lipids are transported from tissues to the liver by ________.
HDL
Which of the following lipoprotein particles has the greatest relative content (percent weight) of proteins? LDL CM VLDL HDL
HDL
Which of the following accurately ranks lipoproteins from highest to lowest density?
HDL > LDL > IDL > VLDL > chylomicrons
Which of the following could be produced by the reaction of two or more of phosphatidic acids with two or more glycerol-3-phosphates? I. phosphatidylglycerol II. cardiolipin III. phosphatidylinositol IV. gangliosides I, II, III, IV II, III I, III I, II III only
I, II
Which of the following is required for entry of fatty acids into the oxidation pathway?I. priming via the enzyme acyl CoA synthetaseII. conservation of free energy from ATP hydrolysis by use of a thioester linkageIII. transport to the cytosol for oxidation via a carnitine carrier proteinIV. hydrolysis of carnitine palmitoyl transfer protein I, II I, II, III I, II, III, IV III, IV I, III
I, II
Sphinganine is an intermediate in the synthesis of which of the following? I. ceramides II. spingomyelins III. cerebrosides IV. prostaglandins I only I, II I, II, III II, III I, II, IV
I, II, III
Cells take up ____ by receptor mediated endocytosis.
LDL
Which of the following lipoprotein particles has the greatest relative content (percent weight) of cholesteryl-esters? CM HDL VLDL LDL
LDL
Which compound is an important biosynthetic precursor of all sphingolipids? Serine Ethanolamine Triacylglycerol Aspartate Glycine
Serine
Free fatty acids bind to ________ for circulation in the bloodstream.
albumin
Digestion of triacylglycerols is aided by the cholesterol derivatives synthesized by the liver known as:
bile acids
The antidiabetes drugs known as thiazolidinediones induce the production of glycerol kinase in adipocytes. This would decrease the concentration of serum fatty acids, which are often elevated in diabetics. Glycerol kinase converts ______ to ________ , a precursor for _______ synthesis. By promoting _______ synthesis, the drug decreases the concentration of unesterified fatty acids in the body.
glycerol; glycerol-3-phosphate; triacylglycerol; triacylglycerol
Where does the process of lipolysis occur? i) skeletal muscle ii) adipose tissue iii) intestine iv) blood vessel walls i and iii i, ii, and iii i, ii, iii, and iv ii, iii, and iv ii and iv
ii, iii, and iv
Fatty acid synthesis requires both acetyl-CoA and ________ as initiator molecules.
malonyl-CoA
Biodiesel, a fuel typically derived from plant oils, can be manufactured by treating the oil with a methanol/KOH mixture to produce fatty acid methyl esters. one _____ ester, two _____ esters, and one ________
palmitoyl methyl; oleoyl methyl; glycerol
Acyl carrier protein (ACP) contains a ________ prosthetic group.
phosphopantetheine
The beta oxidation of odd-numbered fatty acids results in ________ as a final product.
propionyl-CoA