Test
Biochemistry Exam 4 Lipid Metabolism- PMU 2nd Year
Preguntas del test (46)
1Biosynthesis of cholesterol:
- Aoccurs in mitochondria
- Boccurs in cytosol
- Cconsumes hydrogen atoms in the form of NADPH
- Dis accompanied with storage of energy in the form of ATP
- Erequires a large quantity of ATP
2Cholesterol is:
- Aa protein
- Ba lipid
- Can amino acid
- Dcomposed of four rings and a side chain
- Ecomposed of twenty seven carbon atoms
3The key enzyme of cholesterol biosynthesis is:
- AThiolase
- BHMG-CoA synthase
- CHMG-CoA reductase
- DMevalonate kinase
- ESqualene synthetase
4The biosynthesis of triacylglycerols requires:
- Aphospholipase B
- Bphospholipase D
- Ccholesteryl ester molecules
- Dphosphorylated triose (glycerol 3-phosphate)
- Efatty acids in the form of acyl-CoA
5Which of the following is true?
- ATriacylglycerols are formed by acylation of triose phosphates
- BTriacylglycerols are hydrolyzed by lipases
- CTriacylglycerols are polymerized into glycogen
- DTriacylglycerols are storage lipids stored in adipose tissue
- ETriacylglycerols are degraded by acyl-CoA synthase
6Which of the following compounds is not a lipid?
- Acholesterol
- Bglycerol
- Ctriacylglycerol
- Dsphingomyelin
- Ephosphatidylcholine
7Which is the main apoprotein in LDL, recognized by the LDL receptors:
- AApo B-48
- BApo E
- CApo B-100
- DApo C-II
8Which is the main regulatory enzyme in cholesterol biosynthesis:
- AThiolase
- BHMG-CoA reductase
- CHMG-CoA synthase
- DMevalonate kinase
9Which of the following compounds are cholesterol derivatives:
- ABile acids
- BVit. D3
- Csteroid hormones
- DHMG-CoA
- Eketone bodies
10Which of the following is TRUE:
- Aoxidation of fatty acids occurs in mitochondria
- Boxidation of fatty acids occurs in cytosol
- Coxidation of fatty acids generates FADH2 and NADH
- Doxidation of fatty acids is catalyzed by a multifunctionai protein with seven enzyme activities
11Which of the following apoproteins activates lipoprotein lipase:
- AApo B-48
- BApo E
- CApo B-100
- DApo C-II
12What is the effect of the following hormones on lipolysis‘?
- Alipolysis is stimulated by adrenaline
- Blipolysis is inhibited by adrenaline
- Clipolysis is inhibited by insulin
- Dlipolysis is stimulated by insulin
13Which of the following is TRUE:
- AVLDL transport triacylglycerols from the liver to the extrahepatic tissues
- BVLDL deliver cholesterol to the tissues
- CLDL deliver cholesterol to the tissues
- DHDL remove cholesterol from the tissues and return it to the liver for excretion
14Which of the following is not true
- Acholesterol is an essential structural component of cellular membranes
- Bcholesterol is the precursor of steroid hormones, bile acids and vit D3
- CHMG-CoA synthase is the main regulatory enzyme in the pathway of cholesterol biosynthesis
- DHMG-CoA reductase activity is increased by insulin
15Which of the following substances are ketone bodies
- AAcetone
- BAcetoacetate
- CAcetyl-CoA
- DPyruvate
- E3-hydroxybutyrate
16Which of the following statements about LDL are true?
- Acontain only apo B-100
- Bcontain apo B-100 and apo E
- Cthey transport cholesterol from the extrahepatic tissues to the liver
- Dthey transport cholesterol from the liver to the extrahepatic tissues
- Ethey transport triacylglycerols from the liver to the extrahepatic tissues
17Which of the following statements about eicosanoids are FALSE?
- Athey are synthesized and secreted by separate glands
- Bthey have an escpecially fast metabolism
- Ccorticosteroids can block their production
- Dthromboxanes are synthesized through the lipoxygenase pathway
- Ederive only from the arachidonic acid
18Which of the following compounds is not a glycerophospholipid?
- APhosphatidylinositol
- BPhosphatidylserine
- CLecithin
- DGanglioside
19Which of the following statements about biosynthesis of fatty acids and B-oxidation are TRUE
- AAcetyl-CoA, which serves as substrate for the synthesis, derives from B-oxidation
- BB-oxidation and lipogenesis are controlled reciprocally
- CMalonyl-CoA inhibits carnitine-palmitoyl transferase 2 and thus B-oxidation
- DCitrate is an activator of acetyl-CoA carboxylase
20Which of the following statements about ketone bodies are TRUE?
- AKetogenesis occurs when there is an increase in the level of free fatty acids
- BAll ketone bodies serve as an energy fuel for the extrahepatic tissues
- CAcetone and B-hydroxybutirate serve as energy fuel but acetoacetate does not
- DKetone bodies are physiologically present in blood but in a very low concentration
- EThe abnormal increase in the concentration of ketone bodies can cause ketoacidosis
- FHMG-CoA synthase and HMG-CoA lyase are enzymes from the pathway of ketogenesis
21Which of the following about activation of free fatty acids is true?
- Aan enzyme, acetyl-CoA carboxylase, is needed
- Ban enzyme, acyl-CoA synthetase, is needed
- Cthe enzyme is placed in inner mitochondrial membrane
- Dthe enzyme is placed in outer mitochondrial membrane
- EATP is needed as energy donor
22Which of the following is true?
- Along-chain fatty acids are oxidized in mitochondrial matrix
- Bperoxisomes oxidize very long-chain fatty acids
- Cβ-oxidation leads to an activated energy consumption
- Doxidation of fatty acids produces large quantity of NADH and FADH2 which leads to large production of ATP
- Eoxidation of fatty acids produces large quantity of NADPH, which leads to acceleration of anabolic processes
23Which of the following is true?
- ANADPH for fatty acids biosynthesis is generated by the pentose phosphate pathway, mainly
- BNADPH is generated in the B-oxidation, mainly
- Chydrogen atoms, needed for reductive reactions in fatty acids biosynthesis, are produced by the respiratory chain
- Denzyme activities of the acyl synthase complex need NADPH
- ENADPH is also generated by the “malic” enzyme, placed in cytosol
24Which of the following is true?
- Aketone bodies are the main energy source for skeletal muscles
- Bketone bodies are an alternative energy source for extrahepatic tissues
- Cketone bodies enter glycolysis after activation
- Dhigher than normal quantities of ketone bodies in blood cause a condition called ketosis
- Eketosis is mild in starvation but severe in diabetes mellitus
25HMG-CoA reductase
- Ais inhibited by lipids and cholesterol
- Bis activated by phophorylation
- Cinsulin serves both as its activator but also as an inducer an gene level
- Din hypercholesterolaemia can be pharmologically affected by statins
26Which is the only one glucogenic metabolite from the free fatty acids metabolism
- Aacyl-CoA
- Bacetyl-CoA
- Cmalonyl-CoA
- Dpropionyl-CoA
27Which of the following statements about acyl-CoA synthase are NOT TRUE?
- Ain mammals it is a multifunctional complex, organized as a hetrodimer
- Bit functions together with acyl carrier protein, which contains 4-phosphopantethine as a prosthetic group
- Cketoacyl reductase uses NADH+H+ as a cofactor
- Dthe last enzyme is thioesterase
28Which of the following is TRUE:
- Afree fatty acids that arise from Iipolysis of triacylglycerol in adipose tissue are the precursors of ketone bodies
- Bin starvation the insulin/glucagon ratio increases
- Cketosis is mild in starvation but severe in diabetes mellitus
- Dketogenesis occurs in the extrahepatic tissues
29Which of the following is TRUE:
- Athe biosynthesis of fatty acids (lipogenesis) occurs in the cytosol
- Bin mammals the fatty acid synthase complex consists of three identical monomers
- Cthe main source of NADPH for the biosynthcsis of fatty acids is glycolysis
- Dacetyl-CoA carboxylase is the main regulatory enzyme in lipogenesis
30Which of the following is TRUE:
- Aglycerol-3-phosphate and Acyl-CoA are required for the biosynthesis of triacylglycerols
- Bglycerol kinase is active in muscle and adipose tissue
- Cthe degradation of triacylglycerols (lipolysis) is catalyzed by lipase
- Dthe hormone-sensitive lipase is activated by insulin
31Which of the following is TRUE:
- Aeicosanoids can be produced from arachidonic acid
- Bthe NSAIDs like aspirin, ibuprofen and indomethacin activate COX-1 and COX-2
- Carachidonic acid may be obtained from membrane phospholipids by the action of phospholipase A2
- Dthe cyclooxygenase pathway produces prostaglandins
32Which phospholipase is essential for initializing the biosynthesis of eicosanoids?
- Aphospholipase A1
- Bphospholipase A2
- Cphospholipase C
- Dphospholipase D
33Lipolysis:
- Ais the degradation of fatty acids
- Bis the degradation of triacylglycerols
- Coccurs in the mitochondria
- Doccurs in the cytoplasm
- Eis activated by epinephrine and glucagon which dephosphorylate the hormone-sensitive lipase
34Which of the following enzymes do not participate in β-oxidation?
- AHMG-CoA syntahse
- BThiolase
- CThioesterase
- DAcyl-CoA dehydrogenase
- Ehydratase
35Which of the following is TRUE:
- Athe primary bile acids are synthesized in the liver from cholesterol
- Bthe primary bile acids enter the bile as serine or alanine conjugates
- Cthe bile acids emulsify dietary lipids in the small intestine and aid their digestion
- Dthe bile acids emulsify dietary carbohydrates
36Which of the following enzymes participate in β-oxidation
- Aacyl-CoA dehydrogenase
- B3-hydroxyacyl-CoA dehydrogenase
- Cacetyl-CoA carboxylase
- Dthiolase
- EHMG-CoA reductase
37Which of the following statements is TRUE
- Athe fatty acid synthase complex in mammals is a dimer of two identical monomers
- Bthe synthesis of fatty acids (lipogenesis) occurs in the cytosol
- Cacetyl-CoA carboxylase requires pyridoxal phosphate as a cofactor
- Dglucagon activates acetyl-CoA carboxylase by stimulating its phosphorylation
38HMG-CoA reductase:
- Ais inhibited by bile acids and cholesterol
- Bis activated by phosphorylation
- Cinsulin serves both as its activator, but also as an inducer on gene level
- Din hypercholesterolaemia can be pharmocologically affected by statins
39Which of the following statements are FALSE?
- Athe levels of leptin in obesity are high and these of adiponectin- low
- Bthe higher HDL-cholesterol level is, the higher cardio-vascular risk is
- Ca defect in LDL-receptors can cause hypercholesterolaemia
- Da deficiency in vitamin D in adults is called rickets
- Echolelithiasis can be caused by impaired ratio between cholesterol and bile acids as well as phospholipids in the gallbladder
40Hormone-sensitive lipase
- Ais the main regulatory enzyme in β-oxidation
- Bis activated by cAMP-dependent protein kinase (PKA)
- Cis inhibited by insulin- the activator of phosphodieterase
- Dis inhibited by glucagon and the thyroid hormones
- Ecatalyzes the degradation of monacylglycerols to fatty acid and glycerol
- Ffunctions in the mitochondria
41Which of the following compounds is not a phospholipid
- APhosphatidylcortisol
- BPhosphatidylcholine
- CGlycerol-3-Phosphate
- D1, 2 diacylglycerol
42Which of the following statements about chylomicrons are true?
- Atheir specific apoprotein is Apo B-100
- Btheir specific apoprotein is Apo B-48
- Cthey transport cholesterol from the intestines to the extrahepatic tissues
- Dthey transport triacylglycerols from the intestines to the extrahepatic tissues
- Ethey transport triacylglycerols from the liver to the extrahepatic tissues
43Ketone bodies
- Aare synthesized in the cytoplasm of the hepatocytes
- Bcan serve as energy source for the brain
- Ctheir synthesis is increased after feeding
- Dtheir synthesis is pathologically increased in diabetes mellitus
- Ethere is a correlation between their degradation and Krebs cycle
44How is acetyl-CoA carboxylase (ACC) regulated?
- Ait is inhibited by acetyl-CoA
- Bit is inhibited by acyl-CoA
- Cit is activated by dephosphorylation
- Dit is activated by phosphorylation
- EIt is regulated in a coordination with the pyruvate dehydrogenase complex
45Cholesterol
- Acan be degraded only in the peroxisomes of the liver cell
- Btogether with the phospholipids is an essential component of the cell membranes
- Cis the precursor of ketone bodies
- Dthe only possible way of its excretion is through bile and bile acids
- Eits synthesis is under strict hormonal control realized on the level of HMG-CoA synthase
46Which reactions can provide NADPH + H+, necessary both for the synthesis of fatty acids and cholesterol?
- Aα-ketoglutarate dehydrogenase complex
- Bcytosolic isocitrate dehydrogenase
- Cmalic enzyme
- Dmalate dehydrogenase
- Epentose phosphate pathway
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- Biochemistry Exam 4 Lipid Metabolism- PMU 2nd Year
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