Aula Virtual de Biología

Test de conocimientos sobre lípidos

1) Un ácido graso saturado tiene

 Dobles o triples enlaces en su cadena

 Aspecto aceitoso

 sólo enlaces sencillos C-C

2) Un jabón se disuelve en agua dando lugar a micelas. Es debido a:

  Un proceso de saponificación

  Un proceso de esterificación

  Un comportamiento hidrófobo

3) La esterificación del glicerol con ácidos grasos produce:

  Lípidos complejos

 Glicerolípidos

 Acilglicéridos

4) Un aceite está formado por:

 Ácidos grasos insaturados de cadena corta

 Ácidos grasos saturados de cadena larga

 Ácidos grasos saturados de cadena muy corta

5) Identifica el ácido oléico:

6) Los esteres de un ácido graso de cadena larga con sus dos extremos hidrófobos puede ser:

 Glicerina.

 Cera de Abeja.

 Lecitina.

7) La Lecitina...

 Es un derivado del ácido fosfatídico con colina

 Es la fosfatidilserina

 Tiene un estructura derivada de un ácido graso con la esfingosina.

8) Un cerebrósido es...
 Ceramida + glucosa o galactosa.
 Ceramida + ácido fosfórico.
 Una esfingomielina.

9) Las sales que emulsionan las grasas favoreciendo la digestión y absorción intestinal se denominan:

 Esteroles.
 Terpenos.
 Ácidos biliares.

10) En el transporte por sangre y linfa de los lípidos está implicado: 
 El mentol
 El gonano.
 El colesterol.

Test de conocimientos sobre lípidos 1) Un ácido graso saturado tiene Dobles o triples enlaces en su cadena Aspecto aceitoso sólo enlaces sencillos C-C 2) Un jabón se disuelve en agua dando lugar a micelas. Es debido a: Un proceso de saponificación Un proceso de esterificación Un comportamiento hidrófobo 3) La esterificación del glicerol con ácidos grasos produce: Lípidos complejos Glicerolípidos Acilglicéridos 4) Un aceite está formado por: Ácidos grasos insaturados de cadena corta Ácidos grasos saturados de cadena larga Ácidos grasos saturados de cadena muy corta 5) Identifica el ácido oléico: 6) Los esteres de un ácido graso de cadena larga con sus dos extremos hidrófobos puede ser: Glicerina. Cera de Abeja. Lecitina. 7) La Lecitina... Es un derivado del ácido fosfatídico con colina Es la fosfatidilserina Tiene un estructura derivada de un ácido graso con la esfingosina. 8) Un cerebrósido es... Ceramida + glucosa o galactosa. Ceramida + ácido fosfórico. Una esfingomielina. 9) Las sales que emulsionan las grasas favoreciendo la digestión y absorción intestinal se denominan: Esteroles. Terpenos. Ácidos biliares. 10) En el transporte por sangre y linfa de los lípidos está implicado: El mentol El gonano. El colesterol. ----------------------------------------------------------------------------- (9) In order for a receptor to be recycled to the plasma membrane following receptor-mediated endocytosis, the receptor would most likely A. become a component of a secretory vessicle. B. be delivered to the mitochordrial matrix. C. complex with clathrin and diffuse through the cytosol. D. fuse with the lysosome and undergo limited proteolysis. E. return to the endoplasmic reticulum and interact with the signal recognition particle. (10) The farnesyl group that is attached to certain membrane proteins is a metabolic derivative of A. cholesterol. B. glycocholate. C. mevalonate. D. pregnenolone. E. squalene. Grade/regrade this exam (11) The deformation of an erythrocyte that occurs as this cell flows through a capillary is due to A. a calcium-mediated phase transition of specific phospholipid classes. B. extensive changes in phospholipid asymmetry in the membrane. C. interactions between integral and peripheral membrane proteins. D. a loss of proteins that are anchored to the membrane by lipids. (12) The rationale for treating pre-term neonates with surfactant preparations is to A. accelerate the phagocytic activity of alveolar macrophages. B. increase secretion of tubular myelin. C. regulate protein trafficking in the Golgi complex. D. stimulate synthesis of dipalmitoylphosphatidylcholine. E. supplement decreased levels of monolayer lipids and proteins. (13) Branch points in glycogen are formed by A. beta-[1-6] glycosidic links. B. alpha-[1-4] glycosidic links. C. alpha-[1-6] glycosidic links. D. beta-[1-3] glycosidic links. E. alpha-[1-3] glycosidic links. (14) Some of the enzyme-catalyzed steps in the beta-oxidation cycle are chemically similar to those that occur during the A. activation of an amino acid to an amino acyl-tRNA. B. conversion of oxalosuccinate to glyceraldehyde 3-phosphate. C. conversion of succinate to oxaloacetate. D. oxidation of FADH2 to FAD. E. oxidation of glucose to 6-phosphogluconate. (15) An increase in the concentration ratio of insulin to glucagon in the blood will most likely lead to a(n) A. decreased cholesterol synthesis in liver. B. decreased fatty acid synthesis in cardiac muscle. C. increased beta-oxidation of fatty acids in skeletal muscle. D. increased ketone body utilization by brain. E. increased triacylglycerol synthesis in adipose. Grade/regrade this exam (16) The hydrolysis of a phosphatidylinositol 4,5-bisphosphate by a phospholipase C generates which of the following sets of products? A. a phosphorylated inositol and a diacylglycerol B. a phosphorylated inositol and a phosphatidate C. inositol, a ceramide, and inorganic phosphate D. inositol, a diacylglycerol, and inorganic phosphate E. inositol, a fatty acid, and a phosphatidate (17) All of the following are characteristic of cystic fibrosis EXCEPT A. increased viscosity of lung airway secretions. B. decreased fertility in males. C. decreased NaCl levels in sweat. D. decreased intestinal secretion. E. increased clogging of pancreatic ducts. (18) Under anaerobic conditions, a primary product of glycolysis is A. lactate. B. pyruvate. C. glyceraldehyde-3-phosphate. D. ethanol. E. none of the above are correct. (19) During the synthesis of lactosylceramide a likely intermediate would be A. CMP-N-acetylneuraminate. B. CDP-ceramide. C. GDP-mannose. D. UDP-lactose. E. UDP-galactose. (20) An important component of our defense mechanism against damage from partially reduced oxygen anions and their Derivatives is A. superoxide dismutase. B. hydroxide radical. C. isocitrate dehyrodgenase. D. hemoglobin. E. cytochrome a/a3. Grade/regrade this exam (21) As a metabolic intermediate, a long-chain acyl-CoA participates in all of the following reactions or pathways EXCEPT A. ceramide --> ganglioside GM2. B. cholesterol --> cholesteryl ester. C. glycerol3-phosphate--> phosphatidate. D. lysophosphatidylserine --> phosphatidylserine. E. monoacylglycerol --> diacylglycerol. (22) Which of the following lipids is NOT used to anchor proteins to membranes? A. geranylgeranyl group B. glycosylphosphatidylinositol C. myristate D. lysophosphatidylcholine (23) Glucokinase and hexokinase can each phosphorylate glucose to form glucose-6-phosphate. Which of the following statements concerning the properties of these two enzymes is INCORRECT? A. Hexokinase is inhibited by glucose-6- phosphate. B. Hexokinase and glucokinase have similar maximum velocities (Vmax). C. Hexokinase and glucokinase have similar Km D. Glucokinase is inhibited by fructose-6-phosphate. (24) All of the following compounds are considered "high energy" compounds EXCEPT WHICH ONE? A. 1,3-bisphosphoglycerate B. phosphoenolpyruvate C. adenosine monophosphate D. creatine phosphate E. adenosine triphosphate (25) In general, the asymmetric orientation of an integral plasma membrane protein is established A. after partial hydrolysis of the polypeptide in the lysosome. B. during membrane insertion and folding in the endoplasmic reticulum. C. following covalent attachment of a lipid anchor in the endoplasmic reticulum. D. following covalent attachment of oligosaccharide (glycosyl) groups in the Golgi complex. Grade/regrade this exam (26) Commonly found carbohydrates in humans are stereochemically related to which of the following? A. L-alanine B. D-glyceraldehyde C. L-glyceraldehyde D. glycerol E. None of the above is correct. (27) The plasma lipoprotein most likely to transport triacyglycerols from the liver to the heart is the A. chylomicrons. B. VLDL. C. IDL. D. LDL. E. HDL. (28) Interactions between cells and the extracellular matrix may be mediated by A. cholesteryl esters. B. gangliosides. C. monoacylglycerol. D. long-chain acyl-CoAs. E. primary bile salts. (29) During the dilation of blood vessels, nitric oxide acts directly on A. adenylyl cyclase. B. guanylyl cyclase. C. phosphodiesterase in the smooth muscle cell. D. phospholipase C in the macrophage. E. fatty acid synthase in the endothelial cell. (30) NADH is produced in reactions catalyzed by the following enzymes in the tricarboxylic acidcycle EXCEPT WHICH ONE? A. isocitrate dehydrogenase B. malate dehydrogenase C. succinate dehydrogenase D. alpha-ketoglutarate dehydrogenase Grade/regrade this exam (31) An autosomal recessive deficiency of glycosidase -- a lysosomal enzyme that hydrolyzesglycosidic bonds -- could lead to A. changes in lipid asymmetry in mitochondrial membranes. B. cellular accumulation of a ceramide derivative. C. increased phosphorylation of a phosphatidylglycerol. D. decreased secretion of a glycosphingolipid. E. loss of a sphingomyelin from the plasma membrane. (32) The core of N-linked oligosaccharide units in glycoproteins is initially formed as a derivative of______________ before transfer to a suitable glycoprotein acceptor. A. acetyl CoA B. dolichol phosphate C. asparagine D. tyrosine phosphate E. glycerol-3-phosphate (33) The enzymes that catalyze the beta-oxidation of fatty acids function in which cellular compartment? A. endoplasmic reticulum B. Golgi complex C. lysosome D. mitochondrion E. nuclear envelope (34) Which of the following has been shown to be an uncoupling agent for oxidative phosphorylation. A. 2-deoxyglucose B. fluoride ion C. arsenate D. thyroxine E. 2,3 bisphosphoglycerate (35) An individual with a deficiency in the pathway for carnitine synthesis fails to ingest adequate amounts of dietary carnitine. During an overnight fast how would the concentration of ketone bodies in this person's blood change compared to the level of ketone bodies in a normal individual's blood? A. decreased B. increased C. no difference D. insufficient information for prediction Grade/regrade this exam (36) During signal transduction the principal determinant of modulated adenylyl cyclase activity is A. a change in the concentration of 5'-AMP. B. a change in the concentration of cytosolic Ca2+. C. a change in the membrane localization of the enzyme. D. the lifetime of the G-alpha-GTP complex. (37) Which characteristic(s) of triacylglycerols best describe(s) the advantage to the human body to their use as one form of metabolic energy? A. direct access to mitochondria in cardiac muscle. B. easily transported in blood as a complex with albumin. C. fully reduced structure and anhydrous storage in adipose. D. immediate precursor of ketone bodies in skeletal muscle. E. interconvertability with glucose in liver. (38) Deletion of Phe508 in the CFTR protein results in which of the following? A. decreased core glycosylation of the CFTR protein B. defective transcription of the CFTR gene C. incomplete processing of the CFTR protein D. decreased secretion of CFTR protein from the cell E. decreased cAMP binding by the CFTR protein (39) The major connective tissue matrix component that is degraded in patients with emphysema is A. collagen. B. mucopolysaccharide. C. elastin. D. basement membrane. From the following list, choose the enzyme that catalyzes the metabolic proces or reaction (40) cleavage of glucose residues from the non-reducing ends of glycogen chains A. glycogen phosphorylase B. debranching enzyme C. glycogen synthase D. phosphorylase kinase E. phosphoprotein phosphatase Grade/regrade this exam From the following list, choose the enzyme that catalyzes the metabolic proces or reaction (41) inactivation of phosphorylase kinase A. glycogen phosphorylase B. debranching enzyme C. glycogen synthase D. phosphorylase kinase E. phosphoprotein phosphatase From the following list, choose the enzyme that catalyzes the metabolic proces or reaction (42) activation of glycogen phosphorylase A. glycogen phosphorylase B. debranching enzyme C. glycogen synthase D. phosphorylase kinase E. phosphoprotein phosphatase (43) Which of the following enzymes is required for the conversion of dietary triacylglycerol into chylomicron triacylglycerol? A. Acyl- CoA synthetase B. Acyl-CoA: cholesterol acyl transferase C. Hormone-sensitive triacylglycerol lipase D. Lipoprotein lipase E. Lysosomal acid lipase. (44) In normal, healthy humans, eating at conventional times, liver glycogen is at its lowest level A. between 4 am and 8 am. B. between noon and 4 pm. C. between 4 pm and 8 pm. D. between 8 pm and midnight. E. between midnight and 4 am. (45) Which of the following is NOT an intermediate in, or product of, the pentose phosphate pathway? A. NADPH B. CO2 C. ribose-5-phosphate D. NADH E. fructose-6-phosphate Grade/regrade this exam (46) The common disaccharide, sucrose, contains which of the following monosaccharide residues? A. glucose and galactose B. glucose and mannose C. glucose and fructose D. glucose only E. mannose and galactose (47) In the cytosol of cells in the basal (resting) state, most Ca2+ is A. associated with mRNA molecules. B. bound to cationic phospholipids on the cytosolic surfaces of membranes. C. complexed with calmodulin. D. distributed among different isoforms of protein kinase A. (48) The kinetics of protein-mediated transport of D-glucose across a muscle cell's plasma membrane can be described by which of the following velocity-concentration curves? A. B. C. D. (49) An important property of high density lipoproteins is the A. deposition of cholesteryl esters in atherosclerotic lesions. B. transport of glycerophospholipids from liver to intestine. C. transport of triacylglycerols from liver to adipose. D. acquisition of cholesterol and apolipoproteins from other lipoproteins. (50) Both glucagon and epinephrine stimulate __________ and inhibit ________. A. glycogen synthesis/glycogen breakdown B. glycogen breakdown/glycogen synthesis C. glycolysis/gluconeogenesis D. glucose uptake by muscle/glucose release from the liver E. cAMP breakdown/cAMP formation Grade/regrade this exam (51) Which of the following pairs of enzymes is directly involved in the formation and degradation of phosphotyrosine in Proteins? A. ATPase and phosphorylase B. cyclase and monosterase C. kinase and phosphatase D. kinase and phosphodiesterase E. phosphorylase and phosphodiesterase (52) Which of the following sugars is typically NOT FOUND in glycoproteins? A. mannose B. galactose C. N-acetyl glucosamine D. N-acetyl galactosamine E. all of the above are found (53) The conversion of pyruvate to phosphoenolpyruvate in gluconeogenesis requires which of the following enzymes? A. lactate dehydrogenase and pyruvate kinase B. pyruvate dehydrogenase C. glucose-6-phosphate dehydrogenase D. pyruvate carboxylase and phosphoenolpyruvate carboxykinase E. phosphofructokinase and aldolase (54) Positive effectors of gluconeogenesis include all of the following EXCEPT WHICH ONE? A. L-alanine B. ATP C. citrate D. acetyl-CoA E. fructose-2,6-bisphosphate (55) The principal control step for the glycolytic pathway (glycolysis) occurs at which of the following enzyme catalyzed steps? A. aldolase B. glyceraldehyde-3-phosphate dehydrogenase C. enolase D. phosphofructokinase E. triose phosphate isomerase Grade/regrade this exam (56) Which conditions best explain the metabolic ketoacidosis that is characteristic in the untreated insulin-dependent Diabetic? A. decreased triacylglycerol mobilization in adipose and decreased glucose synthesis in liver. B. decreased triacylglycerol mobilization in adipose and increased glucose synthesis in liver. C. increased triacylglycerol mobilization in adipose and decreased glucose synthesis in liver. D. increased triacylglycerol mobilization in adipose and increased glucose synthesis in liver. (57) All of the following observations and clinical test results are consistent with the diagnosis of emphysema EXCEPT A. shortness of breath. B. hypercapnia (increased blood CO2. C. enlarged, barrel-shaped chest. D. hypoxemia (decreased blood oxygen). E. decreased in serum LDH. (58) Two distinct shuttle mechanisms have been defined which are capable of moving electrons from NADH in the cytosol into the mitochondrion. These two shuttles produce different amounts of ATP per pair of electrons from oxidative phosphorylation because A. they operate at different efficiencies depending on the substrates available. B. some tissues have only one of the shuttles, while other tissues may have both. C. only some sources of NADH can feed the malate shuttle. D. the glycerol-phosphate shuttle mechanism uses exclusively lactate. E. the two shuttles feed electrons to different points in the electron transport chain. (59) All of the following are required cofactors in the pyruvate dehydrogenase enzyme complex EXCEPT: A. lipoic acid. B. thiamine pyrophosphate. C. flavin adenine dinucleotide (FAD). D. nicotinamide adenine denucleotide (NAD+). E. All of the above are required. (60) The components of the electron transport chain which are responsible for oxidative phosphorylation are located A. on the inner membrane of the mitochondrion. B. on the outer membrane of the mitochondrion. C. in the matrix of the mitochondrion. D. in the intermembrane space of the mitochondrion. E. in the cytosol of the cell. Grade/regrade this exam (61) Mutations in the CFTR gene result in which of the following? A. decreased chloride mobilization from endoplasmic reticulum membranes B. decreased chloride flux in response to cAMP agonists C. decreased active transport of NaCl D. decreased phosphorylation of CFTR by adenylate cyclase E. decreased levels of intracellular cAMP (62) During fatty acid synthesis a cysteine residue and a pantetheine moiety of fatty acid synthase A. are phosphorylated to achieve short-term regulation. B. chelate Zn2+ in the active site. C. form covalent crosslinks with other protein groups. D. form high-energy intermediates with substrates. E. undergo reversible oxidation and reduction. (63) Medium-chain triacylglycerols, taken orally as an energy source, are beneficial to all of the following EXCEPT A. an individual with lipoprotein lipase deficiency. B. an individual with a defect in apolipoprotein B-100 synthesis. C. an individual with severe diarrhea and fat malabsorption. D. an individual with non-insulin-dependent diabetes mellitus. E. an individual who is 2 days old. (64) Smokers tend to develop emphysema more readily than non- smokers. This is due to oxidation of a methionine residue in A. elastin. B. plumonary collagen. C. neutrophil elastase. D. alpha-1-antitrypsin. E. pancreatic elastase. (65) The addition of a methylxanthine to a cell would A. activate a ligand-gated Ca2+ channel in the plasma membrane. B. decrease the phosphorylation of inositol 1,4,5-trisphosphate. C. lead to an inhibition of adenylyl cyclase. D. maintain elevated activity of protein kinase A. E. stimulate the formation of heterotrimeric G proteins from subunits. Grade/regrade this exam Questions 66 to 68 share a common preface or figure. Your patient has elevated plasma concentrations of cholesterol and triacylglycerols. Xanthomas are observed on the elbows and achilles tendons. Analysis of the VLDL and chylomicron lipoprotein fractions reveals an apolipoprotein E that is different from the apoE of a normal person. The level of LDL in the blood is lower than normal. A liver biopsy shows that the level of the LDL receptor is higher than normal. (66) The elevated plasma cholesterol is most likely a consequence of A. a deficiency of a lysosomal enzyme. B. decreased expression of the gene encoding apolipoprotein B-100. C. increased metabolism of lipoproteins by macrophages. D. normal regulation and activity of the LDL receptor. E. poor interaction between a ligand and its receptor in the liver. Questions 66 to 68 share a common preface or figure. Your patient has elevated plasma concentrations of cholesterol and triacylglycerols. Xanthomas are observed on the elbows and achilles tendons. Analysis of the VLDL and chylomicron lipoprotein fractions reveals an apolipoprotein E that is different from the apoE of a normal person. The level of LDL in the blood is lower than normal. A liver biopsy shows that the level of the LDL receptor is higher than normal. (67) The lower than normal level of LDL cholesterol is most likely a consequence of A. a deficiency of a lysosomol enzyme. B. decreased expression of the gene encoding apolipoprotein B-100. C. increased metabolism of lipoproteins by macrophages. D. normal regulation and activity of the LDL receptor. E. poor interaction between a ligand and its receptor in the liver. Questions 66 to 68 share a common preface or figure. Your patient has elevated plasma concentrations of cholesterol and triacylglycerols. Xanthomas are observed on the elbows and achilles tendons. Analysis of the VLDL and chylomicron lipoprotein fractions reveals an apolipoprotein E that is different from the apoE of a normal person. The level of LDL in the blood is lower than normal. A liver biopsy shows that the level of the LDL receptor is higher than normal. (68) The formation of tendon xanthomas in this patient is most likely a consequence of A. a deficiency of a lysosomal enzyme. B. decreased expression of the gene encoding apolipoprotein B-100. C. increased metabolism of lipoproteins by macrophages. D. normal regulation and activity of the LDL receptor. E. poor interaction between a ligand and its receptor in the liver. (69) Both zinc fingers and SH2 domains A. are found in members of the receptor tyrosine kinase family. B. are localized to exoplasmic regions of plasma membrane proteins. C. are subject to reversible phosphorylation and dephosphorylation. D. direct the interaction of macromolecules in signal transduction pathways. (70) Linolenate, 18:3 (6,9,12), is essential to the human diet because humans lack A. a delta-6-desaturase. B. a delta-9-desaturase. C. a delta-12-desaturase. D. the ability to incorporate more than 2 double bonds in a long-chain fatty acid. E. the ability to synthesize fatty acids longer than 16 carbons. Grade/regrade this exam (71) A substrate for glycogen synthase is A. glucose-6-phosphate. B. glucose-1-phosphate. C. free glucose. D. UDP-glucose. E. None of the above are correct (72) Which of the following would be expected to slow the rate of the tricarboxylic acid cycle? A. AMP and pyruvate B. ATP and NADH C. NAD+ and ADP D. calcium ion E. fumarate (73) The "geneotype-phenotype" correlation associated with cystic fibrosis (CF) refers to which of the following? A. Affected members of a single family usually have different CFTR mutations that give riseto different symptoms. B. Environmental influences usually have an impact on the severity of a genetic disease suchas CF. C. Identical twins with CF who are reared apart with CF would be expected to have differentdisease symptoms. D. The severity of CF depends to a large extent on the specific mutation in the CFTR gene. E. The severity of CF depends on how many chloride channel genes are mutated. (74) The structure shown below represents which of the following? A. D-fructose B. D-mannose C. L-fucose D. D-galactose E. D-glucose (75) Which of the following phenotypes could result from a mutation in the gene that encodes one of the polypeptides clathrin? A. loss of cell shape changes during mitosis B. absence of phospholipid asymmetry in intracellular organelles C. decreased uptake from the extracellular medium of Fe2+ and delivery to cytosol D. increased ATP-dependent movement of Na+ and K+ across the plasma membrane (76) The formation of citrate in the initiation of the tricarboxylic acid cycle involves the condensation of acetyl CoA and A. lactate. B. oxaloacetate. C. succinate. D. glyceraldehyde-3-phosphate. E. oxalosuccinate. (77) The Z-mutation of alpha-1-antitrypsin causes liver cirrhosis in children. This is due to the A. accelerated synthesis of the Z-mutant gene product. B. increased secretion of the Z-mutant gene product. C. intracellular accumulation of the Z-mutant gene product. D. oxidation of the Z-mutant gene product. E. rapid clearance from the circulation of the Z-mutant gene product.