Pregunta 1
Pregunta
Biosynthesis of cholesterol:
Respuesta
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occurs in mitochondria
-
occurs in cytosol
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consumes hydrogen atoms in the form of NADPH
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is accompanied with storage of energy in the form of ATP
-
requires a large quantity of ATP
Pregunta 2
Pregunta 3
Pregunta
The key enzyme of cholesterol biosynthesis is:
Respuesta
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Thiolase
-
HMG-CoA synthase
-
HMG-CoA reductase
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Mevalonate kinase
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Squalene synthetase
Pregunta 4
Pregunta
The biosynthesis of triacylglycerols requires:
Respuesta
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phospholipase B
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phospholipase D
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cholesteryl ester molecules
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phosphorylated triose (glycerol 3-phosphate)
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fatty acids in the form of acyl-CoA
Pregunta 5
Pregunta
Which of the following is true?
Respuesta
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Triacylglycerols are formed by acylation of triose phosphates
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Triacylglycerols are hydrolyzed by lipases
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Triacylglycerols are polymerized into glycogen
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Triacylglycerols are storage lipids stored in adipose tissue
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Triacylglycerols are degraded by acyl-CoA synthase
Pregunta 6
Pregunta
Which of the following compounds is not a lipid?
Respuesta
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cholesterol
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glycerol
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triacylglycerol
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sphingomyelin
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phosphatidylcholine
Pregunta 7
Pregunta
Which is the main apoprotein in LDL, recognized by the LDL receptors:
Respuesta
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Apo B-48
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Apo E
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Apo B-100
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Apo C-II
Pregunta 8
Pregunta
Which is the main regulatory enzyme in cholesterol biosynthesis:
Respuesta
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Thiolase
-
HMG-CoA reductase
-
HMG-CoA synthase
-
Mevalonate kinase
Pregunta 9
Pregunta
Which of the following compounds are cholesterol derivatives:
Respuesta
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Bile acids
-
Vit. D3
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steroid hormones
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HMG-CoA
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ketone bodies
Pregunta 10
Pregunta
Which of the following is TRUE:
Respuesta
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oxidation of fatty acids occurs in mitochondria
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oxidation of fatty acids occurs in cytosol
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oxidation of fatty acids generates FADH2 and NADH
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oxidation of fatty acids is catalyzed by a multifunctionai protein with seven enzyme activities
Pregunta 11
Pregunta
Which of the following apoproteins activates lipoprotein lipase:
Respuesta
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Apo B-48
-
Apo E
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Apo B-100
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Apo C-II
Pregunta 12
Pregunta
What is the effect of the following hormones on lipolysis‘?
Respuesta
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lipolysis is stimulated by adrenaline
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lipolysis is inhibited by adrenaline
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lipolysis is inhibited by insulin
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lipolysis is stimulated by insulin
Pregunta 13
Pregunta
Which of the following is TRUE:
Respuesta
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VLDL transport triacylglycerols from the liver to the extrahepatic tissues
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VLDL deliver cholesterol to the tissues
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LDL deliver cholesterol to the tissues
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HDL remove cholesterol from the tissues and return it to the liver for excretion
Pregunta 14
Pregunta
Which of the following is not true
Respuesta
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cholesterol is an essential structural component of cellular membranes
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cholesterol is the precursor of steroid hormones, bile acids and vit D3
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HMG-CoA synthase is the main regulatory enzyme in the pathway of cholesterol biosynthesis
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HMG-CoA reductase activity is increased by insulin
Pregunta 15
Pregunta
Which of the following substances are ketone bodies
Respuesta
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Acetone
-
Acetoacetate
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Acetyl-CoA
-
Pyruvate
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3-hydroxybutyrate
Pregunta 16
Pregunta
Which of the following statements about LDL are true?
Respuesta
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contain only apo B-100
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contain apo B-100 and apo E
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they transport cholesterol from the extrahepatic tissues to the liver
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they transport cholesterol from the liver to the extrahepatic tissues
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they transport triacylglycerols from the liver to the extrahepatic tissues
Pregunta 17
Pregunta
Which of the following statements about eicosanoids are FALSE?
Respuesta
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they are synthesized and secreted by separate glands
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they have an escpecially fast metabolism
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corticosteroids can block their production
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thromboxanes are synthesized through the lipoxygenase pathway
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derive only from the arachidonic acid
Pregunta 18
Pregunta
Which of the following compounds is not a glycerophospholipid?
Respuesta
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Phosphatidylinositol
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Phosphatidylserine
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Lecithin
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Ganglioside
Pregunta 19
Pregunta
Which of the following statements about biosynthesis of fatty acids and B-oxidation are TRUE
Respuesta
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Acetyl-CoA, which serves as substrate for the synthesis, derives from B-oxidation
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B-oxidation and lipogenesis are controlled reciprocally
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Malonyl-CoA inhibits carnitine-palmitoyl transferase 2 and thus B-oxidation
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Citrate is an activator of acetyl-CoA carboxylase
Pregunta 20
Pregunta
Which of the following statements about ketone bodies are TRUE?
Respuesta
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Ketogenesis occurs when there is an increase in the level of free fatty acids
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All ketone bodies serve as an energy fuel for the extrahepatic tissues
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Acetone and B-hydroxybutirate serve as energy fuel but acetoacetate does not
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Ketone bodies are physiologically present in blood but in a very low concentration
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The abnormal increase in the concentration of ketone bodies can cause ketoacidosis
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HMG-CoA synthase and HMG-CoA lyase are enzymes from the pathway of ketogenesis
Pregunta 21
Pregunta
Which of the following about activation of free fatty acids is true?
Respuesta
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an enzyme, acetyl-CoA carboxylase, is needed
-
an enzyme, acyl-CoA synthetase, is needed
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the enzyme is placed in inner mitochondrial membrane
-
the enzyme is placed in outer mitochondrial membrane
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ATP is needed as energy donor
Pregunta 22
Pregunta
Which of the following is true?
Respuesta
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long-chain fatty acids are oxidized in mitochondrial matrix
-
peroxisomes oxidize very long-chain fatty acids
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β-oxidation leads to an activated energy consumption
-
oxidation of fatty acids produces large quantity of NADH and FADH2 which leads to large production of ATP
-
oxidation of fatty acids produces large quantity of NADPH, which leads to acceleration of anabolic processes
Pregunta 23
Pregunta
Which of the following is true?
Respuesta
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NADPH for fatty acids biosynthesis is generated by the pentose phosphate pathway, mainly
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NADPH is generated in the B-oxidation, mainly
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hydrogen atoms, needed for reductive reactions in fatty acids biosynthesis, are produced by the respiratory chain
-
enzyme activities of the acyl synthase complex need NADPH
-
NADPH is also generated by the “malic” enzyme, placed in cytosol
Pregunta 24
Pregunta
Which of the following is true?
Respuesta
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ketone bodies are the main energy source for skeletal muscles
-
ketone bodies are an alternative energy source for extrahepatic tissues
-
ketone bodies enter glycolysis after activation
-
higher than normal quantities of ketone bodies in blood cause a condition called ketosis
-
ketosis is mild in starvation but severe in diabetes mellitus
Pregunta 25
Pregunta
HMG-CoA reductase
Respuesta
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is inhibited by lipids and cholesterol
-
is activated by phophorylation
-
insulin serves both as its activator but also as an inducer an gene level
-
in hypercholesterolaemia can be pharmologically affected by statins
Pregunta 26
Pregunta
Which is the only one glucogenic metabolite from the free fatty acids metabolism
Respuesta
-
acyl-CoA
-
acetyl-CoA
-
malonyl-CoA
-
propionyl-CoA
Pregunta 27
Pregunta
Which of the following statements about acyl-CoA synthase are NOT TRUE?
Respuesta
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in mammals it is a multifunctional complex, organized as a hetrodimer
-
it functions together with acyl carrier protein, which contains 4-phosphopantethine as a prosthetic group
-
ketoacyl reductase uses NADH+H+ as a cofactor
-
the last enzyme is thioesterase
Pregunta 28
Pregunta
Which of the following is TRUE:
Respuesta
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free fatty acids that arise from Iipolysis of triacylglycerol in adipose tissue are the precursors of ketone bodies
-
in starvation the insulin/glucagon ratio increases
-
ketosis is mild in starvation but severe in diabetes mellitus
-
ketogenesis occurs in the extrahepatic tissues
Pregunta 29
Pregunta
Which of the following is TRUE:
Respuesta
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the biosynthesis of fatty acids (lipogenesis) occurs in the cytosol
-
in mammals the fatty acid synthase complex consists of three identical monomers
-
the main source of NADPH for the biosynthcsis of fatty acids is glycolysis
-
acetyl-CoA carboxylase is the main regulatory enzyme in lipogenesis
Pregunta 30
Pregunta
Which of the following is TRUE:
Respuesta
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glycerol-3-phosphate and Acyl-CoA are required for the biosynthesis of triacylglycerols
-
glycerol kinase is active in muscle and adipose tissue
-
the degradation of triacylglycerols (lipolysis) is catalyzed by lipase
-
the hormone-sensitive lipase is activated by insulin
Pregunta 31
Pregunta
Which of the following is TRUE:
Respuesta
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eicosanoids can be produced from arachidonic acid
-
the NSAIDs like aspirin, ibuprofen and indomethacin activate COX-1 and COX-2
-
arachidonic acid may be obtained from membrane phospholipids by the action of phospholipase A2
-
the cyclooxygenase pathway produces prostaglandins
Pregunta 32
Pregunta
Which phospholipase is essential for initializing the biosynthesis of eicosanoids?
Respuesta
-
phospholipase A1
-
phospholipase A2
-
phospholipase C
-
phospholipase D
Pregunta 33
Respuesta
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is the degradation of fatty acids
-
is the degradation of triacylglycerols
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occurs in the mitochondria
-
occurs in the cytoplasm
-
is activated by epinephrine and glucagon which dephosphorylate the hormone-sensitive lipase
Pregunta 34
Pregunta
Which of the following enzymes do not participate in β-oxidation?
Respuesta
-
HMG-CoA syntahse
-
Thiolase
-
Thioesterase
-
Acyl-CoA dehydrogenase
-
hydratase
Pregunta 35
Pregunta
Which of the following is TRUE:
Respuesta
-
the primary bile acids are synthesized in the liver from cholesterol
-
the primary bile acids enter the bile as serine or alanine conjugates
-
the bile acids emulsify dietary lipids in the small intestine and aid their digestion
-
the bile acids emulsify dietary carbohydrates
Pregunta 36
Pregunta
Which of the following enzymes participate in β-oxidation
Pregunta 37
Pregunta
Which of the following statements is TRUE
Respuesta
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the fatty acid synthase complex in mammals is a dimer of two identical monomers
-
the synthesis of fatty acids (lipogenesis) occurs in the cytosol
-
acetyl-CoA carboxylase requires pyridoxal phosphate as a cofactor
-
glucagon activates acetyl-CoA carboxylase by stimulating its phosphorylation
Pregunta 38
Pregunta
HMG-CoA reductase:
Respuesta
-
is inhibited by bile acids and cholesterol
-
is activated by phosphorylation
-
insulin serves both as its activator, but also as an inducer on gene level
-
in hypercholesterolaemia can be pharmocologically affected by statins
Pregunta 39
Pregunta
Which of the following statements are FALSE?
Respuesta
-
the levels of leptin in obesity are high and these of adiponectin- low
-
the higher HDL-cholesterol level is, the higher cardio-vascular risk is
-
a defect in LDL-receptors can cause hypercholesterolaemia
-
a deficiency in vitamin D in adults is called rickets
-
cholelithiasis can be caused by impaired ratio between cholesterol and bile acids as well as phospholipids in the gallbladder
Pregunta 40
Pregunta
Hormone-sensitive lipase
Respuesta
-
is the main regulatory enzyme in β-oxidation
-
is activated by cAMP-dependent protein kinase (PKA)
-
is inhibited by insulin- the activator of phosphodieterase
-
is inhibited by glucagon and the thyroid hormones
-
catalyzes the degradation of monacylglycerols to fatty acid and glycerol
-
functions in the mitochondria
Pregunta 41
Pregunta
Which of the following compounds is not a phospholipid
Respuesta
-
Phosphatidylcortisol
-
Phosphatidylcholine
-
Glycerol-3-Phosphate
-
1, 2 diacylglycerol
Pregunta 42
Pregunta
Which of the following statements about chylomicrons are true?
Respuesta
-
their specific apoprotein is Apo B-100
-
their specific apoprotein is Apo B-48
-
they transport cholesterol from the intestines to the extrahepatic tissues
-
they transport triacylglycerols from the intestines to the extrahepatic tissues
-
they transport triacylglycerols from the liver to the extrahepatic tissues
Pregunta 43
Respuesta
-
are synthesized in the cytoplasm of the hepatocytes
-
can serve as energy source for the brain
-
their synthesis is increased after feeding
-
their synthesis is pathologically increased in diabetes mellitus
-
there is a correlation between their degradation and Krebs cycle
Pregunta 44
Pregunta
How is acetyl-CoA carboxylase (ACC) regulated?
Respuesta
-
it is inhibited by acetyl-CoA
-
it is inhibited by acyl-CoA
-
it is activated by dephosphorylation
-
it is activated by phosphorylation
-
It is regulated in a coordination with the pyruvate dehydrogenase complex
Pregunta 45
Respuesta
-
can be degraded only in the peroxisomes of the liver cell
-
together with the phospholipids is an essential component of the cell membranes
-
is the precursor of ketone bodies
-
the only possible way of its excretion is through bile and bile acids
-
its synthesis is under strict hormonal control realized on the level of HMG-CoA synthase
Pregunta 46
Pregunta
Which reactions can provide NADPH + H+, necessary both for the synthesis of fatty acids and cholesterol?
Respuesta
-
α-ketoglutarate dehydrogenase complex
-
cytosolic isocitrate dehydrogenase
-
malic enzyme
-
malate dehydrogenase
-
pentose phosphate pathway