biochem- lipids
In comparing fatty acid biosynthesis with ß-oxidation of fatty acids, which of the following statements is incorrect? Select one: a. A thioester derivative of crotonic acid (trans-2-butenoic acid) is an intermediate in the synthetic path, but not in the degradative path. b. A thioester derivative of D-ß-hydroxybutyrate is an intermediate in the synthetic path, not in the degradative path. c. Fatty acid biosynthesis uses NADPH exclusively, whereas ß-oxidation uses NAD+ exclusively. d. Fatty acid degradation is catalyzed by cytosolic enzymes; fatty acid synthesis by mitochondrial enzymes. e. The condensation of two moles of acetyl-CoA in the presence of a crude extract is more rapid in bicarbonate buffer than in phosphate buffer at the same pH; the cleavage of acetoacetyl-CoA proceeds equally well in either buffer.
incorrect: d. Fatty acid degradation is catalyzed by cytosolic enzymes; fatty acid synthesis by mitochondrial enzymes.
Which of the following is not true of the reaction in which malonyl-CoA is produced during fatty acid synthesis? Select one: a. It is stimulated by citrate. b. It requires acyl carrier protein (ACP). c. It requires CO2 (or bicarbonate). d. The cofactor is biotin.
not true: b. It requires acyl carrier protein (ACP).
The conversion of palmitoyl-CoA (16:0) to myristoyl-CoA (14:0) and 1 mol of acetyl-CoA by the beta-oxidation pathway results in the net formation of: Select one: a. 2 FADH2, 2 NADH, and 1 ATP. b. 2 FADH2 and 2 NADH. c. 1 FADH2, 1 NADH, and 1 ATP. d. 1 FADH2 and 1 NADPH. e. 1 FADH2 and 1 NADH.
e. 1 FADH2 and 1 NADH.
Which is the committed step of the cholesterol biosynthesis? Select one: a. Mevalonate to 5-phosphomevalonate b. Acetyl-CoA to acetoacetyl-CoA c. Acetoacetyl-CoA to 3-hydroxi-3-methyl glutaryl-CoA d. 5-phosphomevalonate to 5-pyrophosphomevalonate e. 3-hydroxi-3-methyl glutaryl-CoA to Mevalonate
e. 3-hydroxi-3-methyl glutaryl-CoA to Mevalonate
Which compound is an intermediate of the ß-oxidation of fatty acids? Select one: a. CH3--CH2--CO--CH2--OH b. CH3--CH2--CO--CH2--CO--OPO32- c. CH3-- (CH2)20--CO--COOH d. CH3--CH2--CO--CO--S--CoA e. CH3--CO--CH2--CO--S--CoA
e. CH3--CO--CH2--CO--S--CoA
Which of the following is not specifically required in the synthesis of fatty acids? Select one: a. acetyl-CoA b. biotin c. HCO3- (CO2) d. malonyl-CoA e. NADH
e. NADH
Which factors participate in intestinal lipid digestion? Select one: a. Lipase and ATP b. Lipase, bile acid and CoA c. Lipoprotein lipase and bile acids d. Mucins and phospholipids e. Pancreatic lipase and bile acids
e. Pancreatic lipase and bile acids
Which one of following statements about the fed and fasting metabolic states is correct? Select one: a. In the fasting state adipose tissue synthesizes glucose from the glycerol released by the breakdown of triacylglycerol. b. In the fasting state adipose tissue synthesizes ketone bodies. c. In the fasting state the main fuel for red blood cells is fatty acids released from adipose tissue. d. Ketone bodies provide the main fuel for the central nervous system in the fasting state. e. Plasma glucose is maintained in starvation and prolonged fasting by gluconeogenesis in the liver from the amino acids released by the breakdown of muscle protein.
e. Plasma glucose is maintained in starvation and prolonged fasting by gluconeogenesis in the liver from the amino acids released by the breakdown of muscle protein.
Cholesterol is synthesized from: Select one: a. oxalate. b. malate. c. lipoic acid. d. choline. e. acetyl-CoA.
e. acetyl-CoA.
Which metabolic pathway uses the reaction catalyzed by 3-hydroxy 3-methyl glutaryl-CoA reductase? Select one: a. glycolysis b. synthesis of ketone bodies c. oxidation of fatty acids d. synthesis of fatty acids e. synthesis of cholesterol
e. synthesis of cholesterol
At least how many glucose molecules are necessary to provide the carbon atoms for the biosynthesis of one cholesterol molecule in mammalian tissues? Select one: a. 7 b. 8 c. 9 d. 6 e. 5
9
What is the recommended daily allowance of cholesterol in normal mixed-type diet of adults? Select one: a. 0.5 g b. 1 g c. 2 g d. 10 g e. 100 g
a. 0.5 g
Transport of fatty acids from the cytoplasm to the mitochondrial matrix requires: Select one: a. ATP, carnitine, and coenzyme A. b. ATP, carnitine, and pyruvate dehydrogenase. c. ATP, coenzyme A, and hexokinase. d. ATP, coenzyme A, and pyruvate dehydrogenase. e. carnitine, coenzyme A, and hexokinase.
a. ATP, carnitine, and coenzyme A.
Which of the following is(are) true of the oxidation of 1 mol of palmitate (a 16-carbon saturated fatty acid; 16:0) by the beta-oxidation pathway, beginning with the free fatty acid in the cytoplasm? Select one or more: a. Activation of the free fatty acid requires the equivalent of two ATPs. b. Inorganic pyrophosphate (PPi) is produced. c. Carnitine functions as an electron acceptor. d. 8 mol of FADH2 are formed. e. 8 mol of acetyl-CoA are formed. f. There is no direct involvement of NAD+.
a. Activation of the free fatty acid requires the equivalent of two ATPs. b. Inorganic pyrophosphate (PPi) is produced. e. 8 mol of acetyl-CoA are formed.
Fatty acids are activated to acyl-CoAs and the acyl group is further transferred to carnitine because: Select one: a. Acyl-carnitines are transported across the mitochondrial membrane, but acyl-CoAs do not. b. acyl-CoAs easily cross the mitochondrial membrane, but the fatty acids themselves will not. c. Carnitine is required to oxidize NAD+ to NADH. d. Fatty acids cannot be oxidized by FAD unless they are in the acyl-carnitine form. e. None of the above is true.
a. Acyl-carnitines are transported across the mitochondrial membrane, but acyl-CoAs do not.
Which carbon atom carries the hydroxylic group in cholesterol? Select one: a. C-3 b. C-7 c. C-10 d. C-21 e. C-27
a. C-3
In what form are the C-atoms of cholesterol released from the human body? Select one or more: a. CO2 b. free cholesterol c. cholesteryl esters d. cholate e. bilirubin
a. CO2 b. free cholesterol d. cholate
Which statements are true? Select one or more: a. Cholesterol is formed from HMG-CoA synthesized in the mitochondria b. Cholesterol is formed from HMG-CoA synthesized in the cytosol c. Mevalonate is formed from HMG-CoA by decarboxylation d. NADPH is needed for mevalonate synthesis e. Acetyl-CoA for cholesterol synthesis originates from mitochondria
a. Cholesterol is formed from HMG-CoA synthesized in the mitochondria. d. NADPH is needed for mevalonate synthesis e. Acetyl-CoA for cholesterol synthesis originates from mitochondria
Select the coenzymes needed for the synthesis of fatty acids Select one or more: a. CoA b. NADP c. FAD d. NAD e. biotin
a. CoA b. NADP e. biotin
Select the coenzymes needed for the b-oxidation of fatty acids Select one or more: a. CoA b. NADP c. FAD d. NAD e. thiamine-PP
a. CoA c. FAD d. NAD
Which lipids are essential for the normal function of the alveolar surfactant? Select one or more: a. Dipalmitoyl-phosphatidylcholine b. Oleyl-palmitoyl-phosphatidylcholine c. Cholesteryl-esters d. Phosphatidylethanolamine e. Sphingomyelin
a. Dipalmitoyl-phosphatidylcholine d. Phosphatidylethanolamine
The triacylglycerols (TAG) form spontaneously a stable separate phase in water environment, because: Select one: a. Droplets of TAG cause an increase in the entropy of the water phase, which overcomes the positive change of enthalpy for the disruption of intermolecular interactions between the water molecules b. Droplets of TAG cause a decrease in the entropy of the water phase, which overcomes the positive change of enthalpy for the disruption of intermolecular interactions between the water molecules c. The polar phosphodiester bonds of TAGs are hidden in the core of the molecule and thus these are not accessible for the water molecules to form homogeneous solution d. The TAG molecules bind to each other with significantly stronger forces than the water molecules e. The TAGs are emulsifiers
a. Droplets of TAG cause an increase in the entropy of the water phase, which overcomes the positive change of enthalpy for the disruption of intermolecular interactions between the water molecules
Which of the following statements are valid for the apolipoprotein B-100? Select one or more: a. It is synthesized in the liver b. It is recognized by the LDL-receptor c. It is not present in the structure of VLDL d. It participates in the liver uptake of chylomicron remnants e. It is found in the structure of IDL
a. It is synthesized in the liver b. It is recognized by the LDL-receptor e. It is found in the structure of IDL
Select the factors that cause increase of the plasma LDL-cholesterol level Select one or more: a. LDL-receptor deficiency b. Apo-B100 deficiency c. lipoprotein lipase deficiency d. PCSK9 (proprotein convertase subtilisin-like/kexin type 9) deficiency e. Idol (inducer of degradation of LDL receptor) deficiency
a. LDL-receptor deficiency b. Apo-B100 deficiency
All glycerol-containing phospholipids are synthesized from: Select one: a. phosphatidic acid. b. mevalonate. c. gangliosides. d. ceramide.
a. phosphatidic acid.
The atelectasis in neonatal respiratory distress syndrome is caused by: Select one or more: a. Lack of dipalmitoyl-phosphatidylcholine in the surfactant of the lungs b. Deficient spreading of the phospholipid bilayer on the water-air interface in the alveoli c. Inability of the immature neonatal lung to form lamellar bodies d. High content of saturated fatty acids in the phosphatidylcholine component of the surfactant e. Increased surface tension of the fluid layer of the lungs
a. Lack of dipalmitoyl-phosphatidylcholine in the surfactant of the lungs b. Deficient spreading of the phospholipid bilayer on the water-air interface in the alveoli e. Increased surface tension of the fluid layer of the lungs
Select the substrates of the mammalian phosphatidylserine synthase I Select one or more: a. Phosphatidylcholine b. Phosphatidylethanolamine c. CTP d. Serine e. ATP f. diacylglycerol g. CDP-diacylglycerol
a. Phosphatidylcholine d. Serine
Select the statements valid for the ketone bodies Select one or more: a. Produced in the liver b. Non-soluble in water c. Only organs expressing the ß-ketoacyl-CoA-transferase enzyme can utilize them d. Their amount increases in parallel with the increase of b-oxidation of fatty acids in the liver e. They are not produced under physiological conditions
a. Produced in the liver c. Only organs expressing the ß-ketoacyl-CoA-transferase enzyme can utilize them d. Their amount increases in parallel with the increase of b-oxidation of fatty acids in the liver
Which protein of the SREBP-dependent signalling binds directly cholesterol? Select one: a. SCAP b. SREBP c. INSIG d. SREBP-cleavage protease
a. SCAP
Select the statement, which is most relevant to the maintenance of appropriate ratio of cationic and anionic phospholipids in the membranes Select one: a. The CTP-phosphocholine cytidylyltransferase binds with high affinity to reversed hexagonal phase membranes and with low affinity to ordered gel phase membranes b. The CTP-phosphocholine cytidylyltransferase is inhibited by cationic phospholipids and activated by anionic phospholipids c. The CTP-phosphocholine cytidylyltransferase is active in dephosphorylated state d. Due to its higher negative charge the phosphorylated CTP-phosphocholine cytidylyltransferase binds to membranes with high content of cationic phospholipids e. Anionic phospholipids donate negatively charged phosphate groups to CTP-phosphocholine cytidylyltransferase, which is inhibited in this way
a. The CTP-phosphocholine cytidylyltransferase binds with high affinity to reversed hexagonal phase membranes and with low affinity to ordered gel phase membranes
Select the statements valid for the synthesis of fatty acids Select one or more: a. The activity of acetyl-CoA carboxilase primarily determines the overall rate of the process b. The acetyl-CoA is transported in the form of citrate to the site of synthesis c. NADH2 is utilized in the reactions of the process d. The ATP-citrate-lyase provides the immediate precursor of the synthesis e. The carnitine carrier is involved in the process
a. The activity of acetyl-CoA carboxilase primarily determines the overall rate of the process b. The acetyl-CoA is transported in the form of citrate to the site of synthesis e. The carnitine carrier is involved in the process
Select the correct statements Select one or more: a. The acyl-CoA dehydrogenase is a mitochondrial enzyme b. NAD is the coenzyme of acyl-CoA dehydrogenase c. The acyl-CoA dehydrogenase generates a trans-double bond d. No ketone bodies are produced, if the acyl-CoA dehydrogenase is deficient
a. The acyl-CoA dehydrogenase is a mitochondrial enzyme. c. The acyl-CoA dehydrogenase generates a trans-double bond d. No ketone bodies are produced, if the acyl-CoA dehydrogenase is deficient
Select the correct statements Select one or more: a. The nascent HDL does not contain cholesteryl esters b. Triacylglycerols are transferred from VLDL to HDL c. Cholesteryl esters are transferred from VLDL to HDL d. The hepatic lipase degrades the triacylglycerols in HDL2 e. The HDL-derived cholesterol is taken up by the liver in part in the form of LDL
a. The nascent HDL does not contain cholesteryl esters. b. Triacylglycerols are transferred from VLDL to HDL. d. The hepatic lipase degrades the triacylglycerols in HDL2. e. The HDL-derived cholesterol is taken up by the liver in part in the form of LDL.
What is the mechanism of fatty acid activation? Select one: a. a reaction requiring free CoA and ATP b. binding to carnitine c. formation of UDP-acids d. phosphorylation with ATP e. transfer of CoA from malonyl CoA
a. a reaction requiring free CoA and ATP
Which proteins are needed for the transfer of dietary cholesterol to extrahepatic tissues? Select one or more: a. apoB48 b. apoB100 c. lipoprotein lipase d. acyl-CoA cholesterol acyl transferase e. lecithin cholesterol acyl transferase
a. apoB48 b. apoB100 c. lipoprotein lipase d. acyl-CoA cholesterol acyl transferase
Where is acyl-CoA cholesterol-transferase (ACAT) localized? Select one: a. endoplasmic reticulum membrane b. cytosol c. mitochondrium matrix d. inner mitochondrial membrane
a. endoplasmic reticulum membrane
Select the enzymes involved in the control of the phosphatidylcholine biosynthesis: Select one or more: a. glycerol-3-phosphate acyltransferase b. monoacylglycerol-3-phosphate acyltransferase c. phosphatidate phosphohydrolase d. CTP-phosphocholine cytidylyltransferase e. diacylglycerol-acyltransferase f. choline kinase g. CDP-diacylglycerol phosphocholine transferase
a. glycerol-3-phosphate acyltransferase c. phosphatidate phosphohydrolase d. CTP-phosphocholine cytidylyltransferase f. choline kinase
Which cells express FXR? Select one or more: a. hepatocytes b. enterocytes c. macrophages d. adipocytes e. smooth muscle cells
a. hepatocytes b. enterocytes
The rate of fatty acid synthesis is increased by Select one or more: a. insulin b. long-chain fatty acids c. NADH d. glucagon e. citrate
a. insulin e. citrate
Which statements are true concerning miR-33 microRNA? Select one or more: a. its level increases in cholesterol depletion b. its level increases in cholesterol overload c. it stimulates the translation of ABCA1 (ATP binding cassette A 1 transporter) d. it stimulates the transcription of NPC1 (Nieman-Pick type C 1 protein) e. it suppresses the translation of ABCA1 (ATP binding cassette A 1 transporter)
a. its level increases in cholesterol depletion e. it suppresses the translation of ABCA1 (ATP binding cassette A 1 transporter)
Which of these can be synthesized by plants but not by humans? Select one: a. linoleate [18:2(D9,12)] b. palmitate (16:0) c. phosphatidylcholine d. pyruvate e. stearate (18:0)
a. linoleate [18:2(D9,12)]
Select the statements valid for the lipoproteins Select one or more: a. Their density increases in parallel with their protein content b. Their density is reciprocally proportional to their lipid content c. The core non-polar lipids are surrounded by polar lipids d. All of them contain phospholipids e. Non-polar interactions bind together the lipids in their structure
all are true
Select the statements valid for the metabolism of fatty acids with odd number of carbon atoms Select one or more: a. Acetyl-CoA is formed in the course of oxidation b. Propionyl-CoA is formed in the course of oxidation c. Biotin is required d. Succinyl-CoA is formed in the course of oxidation e. Vitamin B12 is required
all are true.
Select the statements valid for the synthesis of palmitoic acid Select one or more: a. The fatty acid synthase is a cytoplasmic enzyme b. The elongation of the molecule by two carbon atoms is accompanied by the oxidation of two NADPH c. The fatty acyl-group is attached to ACP in the course of the synthesis d. Malonyl-CoA loses a carboxyl group during the process e. Acetyl CoA binds to a SH-group of the condensing enzyme
all are true.
The amount of which enzymes increases following a carbohydrate-rich meal Select one or more: a. Acetyl-CoA carboxylase b. Fatty acid synthase c. ATP-citrate lyase d. glucose-6-phosphate dehydrogenase e. malic enzyme
all.
Which are the enzymes catalyzing the synthesis of fatty acids? Select one or more: a. Acetyl-CoA-carboxylase b. Ketoacyl-reductase c. Malonyl-transacylase d. Acetyl-(acyl) transacylase e. Ketoacyl-synthetase
all.
Which cells express LXR? Select one or more: a. hepatocytes b. enterocytes c. macrophages d. adipocytes e. smooth muscle cells
all.
Which processes are modulated by the amount of intracellular free cholesterol? Select one or more: a. synthesis of bile acids b. down-regulation of LDL-receptors in the membrane c. transfer of cholesterol from the membrane into HDL d. cholesterol synthesis e. synthesis of cholesterol esters
all.
How many Acetyl-CoA molecules are needed for the synthesis of one molecule of cholesterol? Select one: a. 10 b. 18 c. 20 d. 25
b. 18
The enzyme system for adding double bonds to saturated fatty acids requires all of the following except: Select one: a. A mixed-function oxidase. b. ATP. c. Cytochrome b5. d. Molecular oxygen (O2). e. NADPH.
b. ATP.
Which molecule is needed for the transport of fatty acids into the mitochondria? Select one: a. Cardiolipin b. Carnitine c. Carnosine d. Creatine e. Glycine
b. Carnitine
Select the coenzyme needed for both b-oxidation and synthesis of fatty acids Select one: a. Biotin b. CoA c. FAD d. NAD e. NADP
b. CoA
Which of the following is /are true of the ß-oxidation of long-chain fatty acids? Select one or more: a. The enzyme complex that catalyzes the reaction contains biotin. b. FADH2 serves as an electron carrier. c. NADH serves as an electron carrier. d. Oxidation of an 18-carbon fatty acid produces six molecules of propionyl-CoA. e. Oxidation of a 15-carbon fatty acid produces at least one propionyl-CoA.
b. FADH2 serves as an electron carrier. c. NADH serves as an electron carrier. e. Oxidation of a 15-carbon fatty acid produces at least one propionyl-CoA.
Which of the following lipoproteins does not contain triacylglycerols? Select one: a. Chylomicron b. HDL3 c. IDL d. Nascent VLDL e. VLDL
b. HDL3
Which enzymes participate in the metabolism of ketone bodies? Select one or more: a. ATP-citrate-lyase b. HMG-CoA-lyase c. HMG-CoA -synthase d. HMG-CoA-reductase e. Succinyl-CoA-acetoacetate CoA transferase
b. HMG-CoA-lyase c. HMG-CoA -synthase e. Succinyl-CoA-acetoacetate CoA transferase
Which one of following statements about the fed and fasting metabolic states is correct? Select one: a. In the fasting state muscle synthesizes glucose from amino acids. b. In the fed state adipose tissue can take up glucose for synthesis of triacylglycerol because glucose transport in adipose tissue is stimulated in response to insulin. c. Ketone bodies are synthesized in muscle in the fasting state, and the amount synthesized increases as fasting extends into starvation. d. Ketone bodies provide an alternative fuel for red blood cells in the fasting state. e. Plasma glucose is maintained in starvation and prolonged fasting by gluconeogenesis from fatty acids.
b. In the fed state adipose tissue can take up glucose for synthesis of triacylglycerol because glucose transport in adipose tissue is stimulated in response to insulin.
Which one of following statements about the fed and fasting metabolic states is correct? Select one: a. In the fed state muscle can take up glucose for use as a metabolic fuel because glucose transport in muscle is stimulated in response to glucagon. b. In the fed state there is decreased secretion of glucagon in response to increased glucose in the portal blood. c. In the fed state, glucagon acts to increase the synthesis of glycogen from glucose. d. Plasma glucose is maintained in starvation and prolonged fasting by gluconeogenesis from ketone bodies. e. There is an increase in metabolic rate in the fasting state.
b. In the fed state there is decreased secretion of glucagon in response to increased glucose in the portal blood.
Which statements are true regarding the lecithin cholesterol acyl transferase? Select one or more: a. It is one of the enzymes of cholesterol synthesis. b. It forms cholesteryl esters. c. It is localized in the membrane of the endoplasmic reticulum. d. Apo AI is its activator. e. It is active in phosphorylated state.
b. It forms cholesteryl esters. d. Apo AI is its activator.
Select the statements valid for the synthesis of triacylglycerols (TAG) Select one or more: a. In adipose tissue the glycerol-kinase provides the glycerol-3-phosphate for the TAG synthesis b. One of the intermediates of the synthesis in the liver is the phosphatidate c. One of the intermediates of the synthesis in the intestine is the 2-monoacylglycerol d. The TAG synthesized in the adipose tissue is transported to other tissues by VLDL e. The absorption of TAG in the intestine involves synthesis of TAG in the epithelial cells
b. One of the intermediates of the synthesis in the liver is the phosphatidate c. One of the intermediates of the synthesis in the intestine is the 2-monoacylglycerol e. The absorption of TAG in the intestine involves synthesis of TAG in the epithelial cells
Which statements are valid for both phosphatidylserine and phosphatidylinositol-4,5,-bisphosphate? Select one or more: a. Present predominantly in the outer layer of the plasma membrane b. Present predominantly in the inner layer of the plasma membrane c. Anionic phospholipids d. The biosynthesis in mammalian tissues proceeds through diacylglycerol activated with CDP e. The biosynthesis in mammalian tissues proceeds through head group activated with CDP
b. Present predominantly in the inner layer of the plasma membrane c. Anionic phospholipids
Which of the following statements are valid? Select one or more: a. The nascent VLDL is formed in the intestinal epithelial cells b. The VLDL is converted to IDL in the circulation c. The cells recognize the apo B-100 in the structure of VLDL and take up the lipoprotein through it d. The lipoprotein lipase reduces the triacylglycerol content of VLDL e. The apo B-100 of LDL is derived from VLDL
b. The VLDL is converted to IDL in the circulation d. The lipoprotein lipase reduces the triacylglycerol content of VLDL e. The apo B-100 of LDL is derived from VLDL
In what form is cholesterol released by the liver? Select one: a. chylomicron b. VLDL c. LDL d. IDL e. in complex with albumin
b. VLDL
In what form is cholesterol taken up by the liver? Select one or more: a. chylomicron b. chylomicron remnant c. HDL d. LDL e. VLDL
b. chylomicron remnant c. HDL d. LDL
Where is the SREBP regulator domain localized if there is excess cholesterol in the cell? Select one: a. cytosol b. endoplasmic reticulum c. Golgi d. nucleus
b. endoplasmic reticulum
Which statements are true concerning proprotein convertase subtilisin-like/kexin type 9 (PCSK9)? Select one or more: a. it contributes to the intracellular processing of LDL receptors prior their exposure in the membrane b. it stimulates the degradation of LDL receptors c. it triggers the endocytosis of LDL-receptor d. it binds to LDL receptors e. it is a protease that degrades LDL receptors
b. it stimulates the degradation of LDL receptors c. it triggers the endocytosis of LDL-receptor d. it binds to LDL receptors
Where is the 3-hydroxy 3-methyl glutaryl-CoA reductase localized within the cell? Select one: a. cytosol b. membrane of the endoplasmic reticulum c. matrix of mitochondria d. the inner membrane of mitochondria e. the outer membrane of mitochondria
b. membrane of the endoplasmic reticulum
What is the function of the cholesteryl ester transfer protein (CETP)? Select one: a. transfers cholesteryl esters from extrahepatic cells to HDL b. transfers cholesteryl esters from HDL to VLDL c. transfers cholesteryl esters from the intestine to HDL d. transfers cholesteryl esters from HDL to the liver
b. transfers cholesteryl esters from HDL to VLDL
Saturated fatty acids are degraded two carbons at a time, producing acetyl-CoA. Under aerobic conditions, how many ATP molecules would be produced per acetyl-CoA formed? Select one: a. 2 b. 3 c. 4 d. 5 e. 6
c. 4
Which of the following statements apply (applies) to the beta-oxidation of fatty acids? Select one or more: a. The process takes place in the cytosol of mammalian cells. b. Carbon atoms are removed from the acyl chain one at a time. c. Before oxidation, fatty acids must be converted to their CoA derivatives. d. NADP+ is the electron acceptor. e. The products of beta-oxidation can directly enter the citric acid cycle for further oxidation.
c. Before oxidation, fatty acids must be converted to their CoA derivatives. e. The products of beta-oxidation can directly enter the citric acid cycle for further oxidation.
In the disease sprue, vitamin B12 (cobalamin) is poorly absorbed in the intestine, resulting in vitamin B12 deficiency. If each of the following fatty acids were in the diet, for which one would the process of fatty acid oxidation be most affected in a patient with sprue? Select one: a. CH3(CH2)14COOH b. CH3(CH2)12COOH c. CH3(CH2)11COOH d. CH3(CH2)10COOH
c. CH3(CH2)11COOH
Which of the following is true of sphingolipid synthesis? Select one: a. All of the carbon atoms of palmitate and serine are incorporated into sphingosine. b. CDP-sphingosine is the activated intermediate. c. CO2 is produced during the synthesis of ceramide from palmitate and serine. d. Glucose 6-phosphate is the direct precursor of the glucose in cerebrosides. e. Phosphatidic acid is a key intermediate in the pathway.
c. CO2 is produced during the synthesis of ceramide from palmitate and serine.
Select the correct order of enzymes or transporters operating in the disposal of excess cholesterol from the human body? Select one: a. ABCA1 / LCAT / LDL / IDL / BSEP b. ABCA1 / LCAT / LDL / VLDL / BSEP c. ACAT / ABCA1 / HDL / LDL / BSEP d. ABCA1 / LCAT / HDL / CETP / LDL e. ABCA1 / ACAT / LCAT / HDL / LDL
d. ABCA1 / LCAT / HDL / CETP / LDL
Which statements are true regarding the synthesis of cholesterol in mammalians? Select one or more: a. Cholesterol is synthesized only in the liver. b. The rate of cholesterol synthesis is constant. c. Cholesterol inhibits the activity of 3-hydroxy 3-methyl glutaryl-CoA reductase d. Cholesterol inhibits the transcription of 3-hydroxy 3-methyl glutaryl-CoA reductase e. Cholesterol inhibits the degradation of 3-hydroxy 3-methyl glutaryl-CoA reductase
c. Cholesterol inhibits the activity of 3-hydroxy 3-methyl glutaryl-CoA reductase d. Cholesterol inhibits the transcription of 3-hydroxy 3-methyl glutaryl-CoA reductase
A blood sample is taken from a 25-year-old man after he has eaten three slices of toast and a boiled egg. Which one of the following will be at a higher concentration than if the blood sample had been taken after an overnight fast? Select one: a. Alanine b. Glucagon c. Glucose d. Ketone bodies e. Nonesterified fatty acids
c. Glucose
Select the statements valid for the reversed hexagonal structures (HII) of phospholipids Select one or more: a. HII is essential for the normal barrier function of the cellular membranes b. HII is formed mainly by phosphatidylcholine, phosphatidylserine and phosphatidylinositol c. HII is essential for the fusion and rearrangements of membranes d. HII is permanently exposed to the outer surface of the plasma membrane e. HII is formed mainly by phosphatidylethanolamine and diacylglycerol
c. HII is essential for the fusion and rearrangements of membranes e. HII is formed mainly by phosphatidylethanolamine and diacylglycerol
Which of the following statements are valid for the ABCA1 transporter? Select one or more: a. It is the major transporter of bile salts b. Its deficiency causes atherosclerosis because of the elevated levels of LDL-cholesterol c. High intracellular cholesterol content stimulates its transcription d. It is necessary for the efflux of cholesterol from the cells e. It is a scavenger receptor for LDL f. HDL binds to it
c. High intracellular cholesterol content stimulates its transcription d. It is necessary for the efflux of cholesterol from the cells. f. HDL binds to it
Which one of following statements about the fed and fasting metabolic states is correct? Select one: a. Fatty acids and triacylglycerol are synthesized in the liver in the fasting state. b. In the fasting state the main fuel for the central nervous system is fatty acids released from adipose tissue. c. In the fasting state the main metabolic fuel for most tissues comes from fatty acids released from adipose tissue. d. In the fed state muscle cannot take up glucose for use as a metabolic fuel because glucose transport in muscle is stimulated in response to glucagon. e. Plasma glucose is maintained in starvation and prolonged fasting by gluconeogenesis in adipose tissue from the glycerol released from triacylglycerol.
c. In the fasting state the main metabolic fuel for most tissues comes from fatty acids released from adipose tissue.
A blood sample is taken from a40-year-old man has been fasting completely for a week, drinking only water. Which of the following will be at a higher concentration than after a normal overnight fast? Select one: a. Glucose b. Insulin c. Ketone bodies d. Nonesterified fatty acids e. Triacylglycerol
c. Ketone bodies
The following statements are valid for the beta-oxidation of saturated fatty acids with even number of C-atoms: Select one or more: a. localized to the cytosol b. fatty acids must be activated by ketothiolase using ATP c. Malonyl-CoA is an allosteric regulator d. oxidation of 1 mol palmitoic acid to CO2 and water covers the synthesis of 106 mol ATP e. requires vitamin B12 cofactor
c. Malonyl-CoA is an allosteric regulator d. oxidation of 1 mol palmitoic acid to CO2 and water covers the synthesis of 106 mol ATP
Which value approaches most closely the daily rate of cholesterol synthesis in the liver (X) and in the extrahepatic tissues (Y) in adults (70 kg body weight)? Numbers are in mg cholesterol synthesized per kg organ mass. Select one: a. X=10; Y=1000 b. X=100; Y=100 c. X=250; Y=10 d. X=500; Y=1 e. X=1000; Y=0
c. X=250; Y=10
A strategy that is not employed in the synthesis of phospholipids is: Select one: a. condensation of CDP-alcohol with diacylglycerol. b. condensation of CDP-diacylglycerol with alcohol. c. condensation of CDP-diacylglycerol with CDP-alcohol. d. exchange of free alcohol with head group alcohol of phospholipid.
c. condensation of CDP-diacylglycerol with CDP-alcohol.
Carnitine is: Select one: a. a 15-carbon fatty acid. b. an essential cofactor for the citric acid cycle. c. essential for intracellular transport of fatty acids. d. one of the amino acids commonly found in protein. e. present only in carnivorous animals.
c. essential for intracellular transport of fatty acids.
What is the consequence of enhanced IDOL production in the liver? Select one: a. enhanced LDL uptake in the liver b. higher number of LDL-receptors in the hepatocytes c. higher blood plasma LDL level d. lower blood plasma LDL level
c. higher blood plasma LDL level
Palmitoyl-CoA, without intervening catabolic steps, is most directly a precursor of: Select one: a. cholesterol. b. malonyl-CoA. c. sphingosine. d. squalene.
c. sphingosine.
Which of the following statements is /are true regarding the synthesis of fatty acids ? Select one: a. Acyl intermediates are thioesters of a low molecular weight protein called acyl carrier protein. b. CO2 or HCO3- is essential. c. The ultimate source of all the carbon atoms in the fatty acid product is acetyl-CoA. d. All of the above are true.
d. All of the above are true.
Which one of following statements about the fed and fasting metabolic states is correct? Select one: a. In the fasting state glucagon acts to increase the activity of lipoprotein lipase in adipose tissue. b. In the fasting state, glucagon acts to increase the synthesis of glycogen from glucose. c. In the fed state insulin acts to increase the breakdown of glycogen to maintain blood glucose. d. Ketone bodies are synthesized in liver in the fasting state, and the amount synthesized increase as fasting extends into starvation. e. In the fed state there is decreased secretion of insulin in response to increased glucose in the portal blood.
d. Ketone bodies are synthesized in liver in the fasting state, and the amount synthesized increase as fasting extends into starvation.
The major site of formation of acetoacetate from fatty acids is the: Select one: a. Adipose tissue. b. Intestinal mucosa. c. Kidney. d. Liver. e. Muscle.
d. Liver.
If malonyl-CoA is synthesized from radioactive (14C-labeled) carbon dioxide and unlabeled acetyl-CoA, and the labeled malonate is then used for fatty acid synthesis, the final product (fatty acid) will have radioactive carbon in: Select one: a. Every C. b. Every even-numbered C. c. Every odd-numbered C (carboxyl end is C-1). d. No part of the molecule. e. Only the farthest carbon from C-1.
d. No part of the molecule.
A blood sample is taken from a 50-year-old woman after an overnight fast. Which one of the following will be at a higher concentration than after she had eaten a meal? Select one: a. Glucose b. Insulin c. Ketone bodies d. Nonesterified fatty acids e. Triacylglycerol
d. Nonesterified fatty acids
In the synthesis of phosphatidylcholine from phosphatidylethanolamine, the methyl group donor is: Select one: a. a tetrahydrofolate derivative. b. choline. c. methanol. d. S-adenosylmethionine (adoMet). e. serine.
d. S-adenosylmethionine (adoMet).
Which of the following statements concerning the ß-oxidation of fatty acids is true? Select one: a. About 1,200 ATP molecules are ultimately produced per 20-carbon fatty acid oxidized. b. The free fatty acid must be carboxylated in the beta position by a biotin-dependent reaction before the process of beta-oxidation commences. c. Two NADH are produced for each acetyl-CoA. d. The free fatty acid must be converted to a thioester before the process of ß-oxidation commences.
d. The free fatty acid must be converted to a thioester before the process of ß-oxidation commences.
Enzymes that catalyze the synthesis of long chain fatty acids in vertebrate cells: Select one: a. act as seven separate proteins. b. are encoded in mitochondrial genes. c. are localized in the mitochondrial matrix. d. are part of a single polypeptide chain containing several distinct enzyme activities. e. have none of the characteristics above.
d. are part of a single polypeptide chain containing several distinct enzyme activities.
Which process is inhibited, if MTP (microsomal TG transfer protein) inhibitor is used as a drug? Select one: a. TG (triglyceride) transfer into adipocytes b. TG (triglyceride) transfer into hepatocytes c. cholesteryl ester transfer into lipid droplets d. cholesteryl ester transfer into chylomicrons
d. cholesteryl ester transfer into chylomicrons
What is the consequence of increased release of PCSK9? Select one: a. enhanced LDL uptake in hepatocytes b. increased number of LDL receptors in hepatocytes c. lower blood plasma LDL level d. higher blood plasma LDL level
d. higher blood plasma LDL level
Which statements are true concerning Idol (inducer of degradation of LDL receptor)? Select one or more: a. it is a transcription factor controlling PCSK9 (proprotein convertase subtilisin-like/kexin type 9) b. it is a protease that degrades LDL receptor c. it binds LDL receptors extracellularly d. it is under the control of LXR (liver X receptor) e. it stimulates the ubiquitination of LDL receptor
d. it is under the control of LXR (liver X receptor) e. it stimulates the ubiquitination of LDL receptor
Which of these is able to cross the inner mitochondrial membrane? Select one: a. acetyl-CoA b. fatty acyl-carnitine c. fatty acyl-CoA d. malonyl-CoA e. None of the above can cross.
d. malonyl-CoA
The synthesis of both glycerophospholipids and triacylglycerols involves: Select one: a. CDP-choline. b. CDP-diacylglycerol. c. phosphatidate phosphatase. d. phosphatidic acid. e. phosphoethanolamine
d. phosphatidic acid.
The following fatty acid, in which the indicated carbon is labeled with 14C, is fed to an animal: 14CH3(CH2)9COOHAfter allowing 30 minutes for fatty acid ß-oxidation, the label would most likely be recovered in: Select one: a. acetyl-CoA. b. both acetyl-CoA and propionyl-CoA. c. palmitoyl-CoA. d. propionyl-CoA.
d. propionyl-CoA.
What is the function of scavenger receptor B1 (SR-B1)? Select one: a. LDL endocytosis b. HDL endocytosis c. selective uptake of LDL-cholesterol d. selective uptake of HDL-cholesterol
d. selective uptake of HDL-cholesterol
CDP-diglyceride is not involved in the biosynthesis of: Select one: a. phosphatidylcholine. b. phosphatidylglycerol. c. phosphatidylserine. d. sphingomyelin.
d. sphingomyelin.
A fatty acid with an odd number of carbons will enter the citric acid cycle as acetyl-CoA and: Select one: a. butyrate. b. citrate. c. malate. d. succinyl-CoA. e. a-ketoglutarate.
d. succinyl-CoA.
The rate-limiting step in fatty acid synthesis is: Select one: a. condensation of acetyl-CoA and malonyl-CoA. b. formation of acetyl-CoA from acetate. c. formation of malonyl-CoA from malonate and coenzyme A. d. the reaction catalyzed by acetyl-CoA carboxylase. e. the reduction of the acetoacetyl group to a ß-hydroxybutyryl group.
d. the reaction catalyzed by acetyl-CoA carboxylase.
Which of the following is not true regarding the oxidation of 1 mol of palmitate (16:0) by the beta-oxidation pathway? Select one: a. ATP is needed. b. 8 mol of acetyl-CoA are formed. c. AMP and PPi are formed. d. 8 mol of FADH2 are formed. e. The reactions occur in the mitochondria.
not true: d. 8 mol of FADH2 are formed.
hich of the following is not true of both the fatty acid synthase system and the fatty acid ß-oxidation system? Select one: a. A derivative of the vitamin pantothenic acid is involved. b. Acyl-CoA derivatives are intermediates. c. Double bonds are oxidized or reduced by pyridine nucleotide coenzymes. d. The processes occur in the mitochondrial matrix.
not true: d. The processes occur in the mitochondrial matrix.
Which of the following is not true of the fatty acid elongation system of vertebrate cells? Select one: a. It involves the same four-step sequence seen in the fatty acid synthase complex. b. It is located in the smooth endoplasmic reticulum. c. It produces stearoyl-CoA by the extension of palmitoyl-CoA. d. It uses malonyl-CoA as a substrate. e. The immediate precursor of the added carbons is acetyl-CoA.
not true: e. The immediate precursor of the added carbons is acetyl-CoA.
Select the compounds, which are not classified as ketone bodies Select one or more: a. Dihydroxyacetone b. Acetoacetate c. b-hydroxybutyrate d. a-hydroxibutyrate e. oxaloacetate
not: a. Dihydroxyacetone d. a-hydroxibutyrate e. oxaloacetate
Which of the following statements is not valid? Select one: a. Cholesterol overload inhibits the expression of LDL-receptors b. Cholesterol overload inhibits the HMG-CoA reductase in the cells c. In case of cholesterol overproduction cholesteryl esters are formed in the cells as a result of the action of LCAT enzyme d. The LDL-derived cholesterol affects the cholesterol synthesis in the cells e. The LDL-receptor recognizes the apo B-100
the wrong one: c. In case of cholesterol overproduction cholesteryl esters are formed in the cells as a result of the action of LCAT enzyme
Which of the following statements is not valid for the lipoprotein lipase? Select one: a. An isoenzyme with a low KM is present in the mammary gland b. It degrades the majority of plasma triacylglycerols c. It is bound to the luminal surface of the capillary endothelial cells d. Its activity increases in the fasting state e. VLDL carries its cofactor
the wrong one: d. Its activity increases in the fasting state
Which of these statements about the regulation of cholesterol synthesis is not true? Select one: a. Cholesterol acquired in the diet has essentially no effect on the synthesis of cholesterol in the liver. b. Failure to regulate cholesterol synthesis predisposes humans to atherosclerosis. c. High intracellular cholesterol stimulates formation of cholesterol esters. d. Insulin stimulates HMG-CoA reductase. e. Cholesterol exerts a negative feedback effect on HMG-CoA reductase.
wrong: a. Cholesterol acquired in the diet has essentially no effect on the synthesis of cholesterol in the liver.
Select the wrong statement Select one: a. HDL carries ACAT (acyl-CoA cholesterol acyltransferase) b. HDL takes up triacylglycerols with the help of cholesteryl ester transfer protein c. HDL2 delivers cholesterol to the liver d. The HDL contains apo-A1 e. The triacylglycerol content of HDL2 is higher than that of HDL3
wrong: a. HDL carries ACAT (acyl-CoA cholesterol acyltransferase)