Exam 2 Practice Exams Flashcards
Please choose the correct statement:
a. Aldolase catalyzes an irreversible reaction
b. Triose isomerase converts dihydroxyacetone-3-phosphate to glyceraldehyde-3-phosphate in an ATP-dependent reaction
c. The net yield of ATP from one mole of glucose that processed completely through the glycolytic pathway is 4 moles of ATP
d. Two moles of NADH are produced by the enzyme, glyceraldehyde-3-phosphate dehydrogenase, for every mole of glucose that proceeds completely through the glycolytic pathway
d. Two moles of NADH are produced by the enzyme, glyceraldehyde-3-phosphate dehydrogenase, for every mole of glucose that proceeds completely through the glycolytic pathway
Please choose the correct statement:
a. The pace of glycolysis is set by the enzyme hexokinase
b. During gluconeogenesis, non-carbohydrates like amino acids can be used to ultimately synthesize the glucose
c. Muscle cells release glucose times of starvation (low blood glucose) in order to supply the brain and red blood cells with this fuel
d. Pyruvate carboxykinase is a mitochondrial enzyme that catalyzes the reaction in which pyruvate is synthesized from oxaloacetate
b. During gluconeogenesis, non-carbohydrates like amino acids can be used to ultimately synthesize the glucose
Please choose the true statement:
a. Biotin is a carrier of nitrogen
b. Folate is a carrier of carbon dioxide
c. Coenzyme A carries acyl groups by way of thirster formation
d. Two vitamins that do not function as cofactors are NADH and FADH2
e. All of the above are true
f. Only b, c, and d are true
g. Only b and c are true
c. Coenzyme A carries acyl groups by way of thirster formation
Please choose the true statement:
a. The two enzymes that catalyze the first reaction of glycolysis are Hexokinase and Glucokinase
b. In glycolysis, the enzyme that catalyzes the substrate phosphorylation of ADP to ATP and pyruvate is pyruvate synthetase
c. Aldolase catalyzes the formation of fructose 6-phosphate
d. Glycolysis occurs in the mitochondrion
a. The two enzymes that catalyze the first reaction of glycolysis are Hexokinase and Glucokinase
FADH2 is oxidized to form FAD by means of hydride transfer to a substrate, and the substrate is thereby reduced.
a. True
b. False
b. False
Please choose the correct statement:
a. Porphobilinogen deaminase deficiency results in acute intermittent porphyria, which is caused by an increase in porphobilinogen and δ-aminolevulinate
b. During heme synthesis, the intermediate porphobiligen is formed glycine and succinyl CoA
c. When heme is degraded, the iron ion, Fe2+, is released
d. Conjugated bilirubin in which 2 fructose molecules have been added to the propionate groups, a process which happens in the spleen
a.Porphobilinogen deaminase deficiency results in acute intermittent porphyria, which is caused by an increase in porphobilinogen and δ-aminolevulinate
Bilirubin reductase catalyzes the reduction of the bilirubin central methane bridge to form biliverdin, which is carried in the blood by serum albumin
a. True
b. False
b. False
Please choose the true statement:
a. Unconjugated bilirubin can be a sign of neonatal jaundice
b. The heme breakdown product, 1-stercobilin, is excreted in feces, while 1-urobilin is excreted in urine
c. Congenital erythropoietic porphyria is the result of the formation of uroporphyrnogen I, which is a symmetric and useless ring structure; this occurs due to insufficient uroporphyrinogen III synthase concentration or activity
d. In the reaction catalyzed by phorphobiligen deaminase, 4 molecules of phorphobilinogen condense head to tail to form a linear tetrapyrrole molecule
e. All of the above are true
f. Only a, b, and c are true
e. All of the above are true
Please choose the false statement:
a. Enzymes stabilize the transition state
b. Enzymes increase the rate of a reaction
c. Enzymes increase the amount of products made at equilibrium
d. Enzymes may be protein or RNA or both
c. Enzymes increase the amount of products made at equilibrium
Please select the true statement:
a. Catalysis by carbonic anhydrase includes acidification of CO2 bound to a zinc ion in the active site
b. Zinc is coordinated in the active site of carbonic anhydrase by pyrrole nitrogens
c. The pyruvate dehydrogenase complex is a mitochondrial complex that consists of multiple copies of E1, E2, and E3
d. The pyruvate dehydrogenase complex produces pyruvate and is part of the gluconeogenic pathway
c. The pyruvate dehydrogenase complex is a mitochondrial complex that consists of multiple copies of E1, E2, and E3
Please select the true statement
a. Glucose is a monosaccharide that is a hexose and a ketone
b. Fructose is a monosaccharide that is a pentose and an aldose
c. Ribose is a monosaccharide that is a pentose and an aldose
d. Mannose is a monosaccharide that is a hexose and a ketose
c. Ribose is a monosaccharide that is a pentose and an aldose
Folic acid (folate) is important for fetal neural tube development
a. True
b. False
a. True
Please choose the true statement:
a. Some vitamins are metals
b. A prosthetic group is a cofactor that is tightly bound to its enzyme whereas a coenzyme is loosely bound
c. An apoenzyme is an enzyme that contains its required prosthetic group
d. Vitamin C is an electron carrier in redox reaction
b. A prosthetic group is a cofactor that is tightly bound to its enzyme whereas a coenzyme is loosely bound
Please choose the true statement (two are true):
a. The anomeric carbon in ketone sugars is carbon 1
b. Alpha and beta anomie’s arise when the anomeric carbon is attacked during ring closure
c. Sucrose is a reducing disaccharide made up of glucose and fructose
d. Lactose is a reducing disaccharide made up of glucose and galactose
b. Alpha and beta anomie’s arise when the anomeric carbon is attacked during ring closure
d. Lactose is a reducing disaccharide made up of glucose and galactose
Please choose the true statement:
a. Glucagon response in the liver results in inhibition of gluconeogenesis
b. Glucagon response in the liver results in inhibition of phosphofructokinase 2
c. Glucagon response in the liver results in activation of hexokinase
d. All of the above are true
b. Glucagon response in the liver results in inhibition of phosphofructokinase 2
Flavin adenine dinucleotide is a vitamin derivative that participates in redox reactions
a. True
b. False
a. True
Please choose the correct statement:
a. Stereoisomers are isomers that have different configurations
b. Epimers are stereoisomers that are mirror images of another
c. Diastereoisomers are stereoisomers that are not mirror images of one another
d. Enantiomers are diastereomers differing at only one asymmetric carbon
e. All of the above are true
f. Only a and c are true
g. Only a, c, and d are true
f. Only a and c are true
Please choose the true statement:
a. Enzymes lower the energy of the products
b. Enzymes increase the concentration of product at equilibrium
c. Enzymes are catalysts that are consumed in the reaction
d. Enzymes function in many cases by stabilizing the transition state during a reaction
d. Enzymes function in many cases by stabilizing the transition state during a reaction
Which two enzymes bypass the pyruvate kinase roadblock during gluconeogenesis?
a. Pyruvate dehydrogenase complex, pyruvate carboxylase
b. Phosphoenolpyruvate carboxykinase, pyruvate carboxylase
c. Alpha-ketoglutarate dehydrogenase, pyruvate dehydrogenase complex
d. The correct two enzymes are not given
b. Phosphoenolpyruvate carboxykinase, pyruvate carboxylase
Which of the following correctly describes the function of pyruvate carboxylase?
a. This enzyme functions in the mitochondrion and requires biotin
b. This enzyme catalyzes the addition of activated carbon dioxide to oxaloacetate to make phosphoenolpyruvate
c. Pyruvate is transformed to oxaloacetate, which is transported directly to the cytoplasm
d. Only a and c are true
a. This enzyme functions in the mitochondrion and requires biotin
Insulin is released from the pancreas when blood glucose levels are high, and glycogen is released from the pancreas when blood glucose levels are low.
a. True
b. False
a. True
The lock and key theory of substrate binding says that complementarity of the enzyme for its substrate exists in the enzyme itself before binding the substrate
a. True
b. False
a. True
Please select the true statement:
a. Galactose in the liver and muscle enters glycolysis at the level of glyceraldehyde
b. During galactose catabolism, the products of the aldose reaction are glycerol-3-phosphate and dihydroxyacetone
c. During fructose catabolism in the muscle and liver, the enzyme phosphofructokinase 1 is bypassed
d. Only a and c are true
e. Only a and b are true
c. During fructose catabolism in the muscle and liver, the enzyme phosphofructokinase 1 is bypassed
What three major ways to replenish the stores of NAD+ to allow the continuation of glycolysis:
a. Anaerobic fermentation, to produce alcohol and NAD+, anaerobic production of lactate and NAD+, and aerobic oxidation in the electron transport chain
b. Aerobic production of lactate and NAD+, anaerobic fermentation to alcohol and NAD+, and aerobic oxidation in the electron transport chain
c. Aerobic production of lactate and NAD+, and anaerobic oxidation in the electron transport chain, and anaerobic fermentation, to produce alcohol and NAD+
a. Anaerobic fermentation, to produce alcohol and NAD+, anaerobic production of lactate and NAD+, and aerobic oxidation in the electron transport chain
Which three glycolytic enzymes catalyze regulated steps?
a. Hexokinase (HK)
b. Phosphofructokinase (PFK or PFK1)
c. Pyruvate kinase (PK)
In a bifunctional enzyme that regulates glycolysis, which of these enzyme functionalities down regulates glycolysis?
Fructose Bisphosphatase
Which glycolytic enzyme is regulated through feed-forward regulation?
PK by F1,6 BP
Please write the first committed step of glycolysis. Be sure to include all reactants, products, and the enzyme catalyst.
F 6-P + ATP catalyzed by PFK1 and yielding F 1,6 BP + BP + ADP + H+
List the five cofactors that are used in the pyruvate dehydrogenase complex
a. Thiamine pyrophosphate (TPP)
b. Lipoamide
c. Coenzyme A (CoA)
d. FAD
e. NAD+
In what sub cellular compartment does heme synthesis begin and end?
Mitochondrion
In what organ does heme degradation begin?
Spleen
Please list the vitamin deficiency for each pathological condition:
a. Osteomalacia b. Pellagra c. Beriberi d. Poor night vision e. Scurvy
a. Osteomalacia - vitamin D
b. Pellagra - vitamin B2 (niacin)
c. Beriberi - vitamin B1 (thiamine)
d. Poor night vision - vitamin A
e. Scurvy - vitamin C
Please state the effect of a non-competitive inhibitor on:
a. KM relative to KMapp b. Vmax relative to Vmaxapp
a. KM relative to KMapp = KM = KMapp
b. Vmax relative to Vmaxapp = Vmax > Vmaxapp
The gluconeogenic enzyme fructose 1,6-bisphosphatase catalyzes a reaction that bypasses PFK1
a. True b. False
a. True
Please choose the true statement:
a. The pyruvate dehydrogenase complex (PDC) is an enzyme complex found in the cytosol b. One of the roles of the PDC is to produce the activated metabolite acetyl CoA c. The PDC requires the electron carrier, thiamine pyrophosphate, to reduct FAD to produce FADH2 d. The PDC is not affected directly or indirectly by the global signals, insulting, and glucagon
b. One of the roles of the PDC is to produce the activated metabolite acetyl CoA
Please choose the true statement:
a. The pace of glycolysis is largely determined by the rate of hexokinase b. The enzyme pyruvate kinase is allosterically activated by fructose 1,6-bisphosphate c. ATP is one of the products of the reaction catalyzed by phosphofructokinase d. Aldose catalyzes a reaction that directly produces glycerol and dihydroxyacetone phosphate
b. The enzyme pyruvate kinase is allosterically activated by fructose 1,6-bisphosphate
Please choose the true statement:
a. Enzymes lower the energy of the final products of the reaction b. Enzymes increase the ratio of molar concentrations of products and reactants at equilibrium c. Enzymes are catalysts that are consumed in a reaction d. Enzymes lower the activation energy of a reaction by stabilizing the transition state
d. Enzymes lower the activation energy of a reaction by stabilizing the transition state
The role of FAD is:
a. To carry nitrogen groups b. To carry single carbons c. To carry electrons transferred as a hydride ion d. To carry electrons transferred as hydrogen atoms
d. To carry electrons transferred as hydrogen atoms
The cofactor Coenzyme A is a derivative of which vitamin?
a. Vitamin A b. Riboflavin c. Niacin d. Pantothenic acid e. Thiamin
d. Pantothenic acid
Which of the vitamins is not water soluble?
a. Vitamin A b. Riboflavin c. Niacin d. Pantothenic acid e. Thiamin
a. Vitamin A
Please choose the reaction classification that is not correctly paired with events occurring in those reactions:
a. Lyase: ATP-dependent covalent bond cleavage b. Oxidation-reduction (redox): electron transfer c. Hydrolysis: covalent bond cleavage through water addition d. Ligation: ATP-dependent covalent bond formation
a. Lyase: ATP-dependent covalent bond cleavage
Please choose the true statement:
a. Glucose is a hexose and a ketose b. Fructose is a pentose and and aldose c. Ribose is a pentose and an aldose d. Mannose is a hexose and a ketose
c. Ribose is a pentose and an aldose
Please select the true statement:
a. δ-aminolevulinate synthase catalyzes a reaction that is the first and rate-limiting step in heme synthesis b. δ-aminolevulinate synthase catalyzes a reaction that occurs in the the cytosol c. δ-aminolevulinate synthase catalyzes a reaction that uses serine as one of the reactants d. All of the above are true e. Only a and c are true
a. δ-aminolevulinate synthase catalyzes a reaction that is the first and rate-limiting step in heme synthesis
Finish this statement regarding gluconeogenesis: During gluconeogenesis……
a. ….phophoenolpyruvate is produced in the mitochondrion b. ….liver, kidney, and muscle cells make free glucose to be sent to other part of the body c. ….pyruvate carboxylase uses CO2 in oxaloacetate synthesis d. ….oxaloacetate is transported through the inner mitochondrial membrane to form malate in the cytosol
c. ….pyruvate carboxylase uses CO2 in oxaloacetate synthesis
Please select the false statement:
a. High levels of unconjugated bilirubin can be a sign of neonatal jaundice, anemia, or the resolution of a larger hematoma b. Breakdown of hemoglobin begins primarily in the spleen c. Bilirubin is a hydrophobic metabolite of heme degradation that is transported to the liver as bilirubin-digluconuronide d. The heme degradation product, 1-stercobilin, is excreted in the feces
c. Bilirubin is a hydrophobic metabolite of heme degradation that is transported to the liver as bilirubin-digluconuronide
Which of the following is not a characteristic of enzyme binding clefts? A binding cleft…
a. ….binds substrates through many strong interactions b. ….may adopt a different shape following binding of its substrate c. ….takes up only small portion of the total enzyme d. ….provides a favorable microenvironment for the reaction to occur
a. ….binds substrates through many strong interactions
Pyruvate contains 4 carbons; the acetyl group in acetyl CoA has 3 carbons.
a. True b. False
b. False
Please choose the true statement:
a. Biotin is a carrier of nitrogen b. Folate is a carrier of carbon dioxide c. Coenzyme A carries acyl groups by way of thioester formation d. Two vitamin derivatives that do not function as cofactors are NADH and FADH2
c. Coenzyme A carries acyl groups by way of thioester formation
One of the hallmarks of non-competitive inhibitors is KM= KMapp, and Vmax is less than Vmaxapp.
a. True b. False
b. False
Please choose the true statement:
a. The two enzymes that catalyze the first reaction of glycolysis are hexokinase and glucokinase b. In glycolysis, the enzyme that catalyzes the substrate phosphorylation of ADP to form ATP and pyruvate is pyruvate synthetase c. Aldolase catalyzes the formation of fructose 6-phosphate d. Glycolysis occurs in the mitochondrion
a. The two enzymes that catalyze the first reaction of glycolysis are hexokinase and glucokinase
Please choose the correct statement:
a. An apoenzyme is an enzyme that contains its required cofactors b. Isoenzymes are forms of an enzyme that may differ in regulation, kinetic parameters, location or time of expression c. Phosphorylation always results in inactivation, as it radically changes protein conformation d. The Km of an enzyme is the same for all of its substrate, because it is a characteristic of the enzyme itself
b. Isoenzymes are forms of an enzyme that may differ in regulation, kinetic parameters, location or time of expression
Please choose the true statement (there are two):
a. Negative feedback by heme reduces translation of δ-aminolevulinate synthase mRNA b. Congenital erythropoietic porphyria generally results from a deficiency in uroporphryinogen III synthase c. Ferric ion, Fe3+ is chelated into a heme ring by ferrochelatase d. Porphobilinogen deaminase deficiency results in a decrease in phorphobilinogen and δ-amnolevulinate
a. Negative feedback by heme reduces translation of δ-aminolevulinate synthase mRNA
b. Congenital erythropoietic porphyria generally results from a deficiency in uroporphryinogen III synthase
Please choose the answer that completes a true statement. In the pyruvate dehydrogenase complex….
a. ….lipoamide is used to carry electrons b. ….pyruvate is a reactant and acetyl CoA is a product c. ….NAD+ is used to oxidize dihydrolipoamide d. ….FADH is used to reduce NAD+
b. ….pyruvate is a reactant and acetyl CoA is a product
Vitamins are essential nutrients that are needed in trace amounts in the diet.
a. True b. False
a. True
Please choose the answer that completes a true statement: During gluconeogenesis…
a. ….glucose 6-P is made in the muscles b. ….pyruvate carboxylase, with its cofactor, biotin, adds a carbon to pyruvate to make oxaloacetate, in a reaction that requires ATP c. ….phosphoenolpyruvate carboxykinase uses decarboxylation of oxaloacetate and GTP to form phosphopyruvate d. All of the above are true e. Only a and b are true
d. All of the above are true
Which of the following is caused by a defect in porphobilinogen deaminase?
a. Acute intermittent porphyria b. Congenital erythropoietic porphyria c. Survy d. Beriberi
a. Acute intermittent porphyria
The Michaelis-Menten constant Km is equal to 1/2 Vmax and is expressed in units of concentration sec-1
a. True b. False
b. False
Please write the vitamin associated with this pathologic deficiency:
a. Beriberi b. Neural tube defect
a. Beriberi - thiamine (B1)
b. Neural tube defect - Folic acid (folate, B9)
Please state the enzyme that catalyzes the reaction that comes after the aldolase reaction in glycolysis:
Triose phosphate isomerase (TPI) / Glyceraldehyde 3 -P dehydrogenase
Please write the reaction that is the first committed step in glycolysis and include the enzyme catalyst
F6P + ATP yields F1,6BP + ADP + H+
PFKI catalyst
Please name the two reactants of the first reaction in heme synthesis:
Succinyl CoA
Glycine
Please name one condition for which high serum unconjugated bilirubin is an indicator
Resolution of a large hematoma, neonatal jaundice, anemia
Please list the lipid soluble vitamins
Vitamin A, Vitamin D, Vitamin E, Vitamin K
NADH is used as a source of electrons to reduce pyruvate during formation of lactic acid
a. True b. False
a. True
The reaction catalyzed by aldolase in glycolysis requires ATP
a. True b. False
b. False
Please select the true statement:
a. The main function of vitamin D is as an antioxidant b. Thiamine is a B vitamin that becomes derivatized to form a carrier of nitrogen groups c. Vitamin E is a water-soluble vitamin d. The main function of Vitamin C is to carry acyl groups e. None of the above is true
e. None of the above is true
Please select the true statement:
a. Addition of a competitive inhibitor does not change an enzyme’s KM for its substrate b. When measuring the velocity of a catalyzed reaction, it is important to wait until the reaction has come to equilibrium first c. Increasing the concentration of substrate has no effect on the rate of a catalyzed reaction d. All of the above are true e. None of the above are true
e. None of the above are true
Please select the true statement:
a. NAD+ acts as a prosthetic group in many enzymes b. A holoenzyme does not contain its cofactor c. RNA can act to catalyze reactions d. All of the above are true e. Only a and c are true
c. RNA can act to catalyze reactions
Please select the true statement:
a. Hexokinase catalyzes addition and removal of phosphate groups from C6 of six-carbon sugars b. Fructose 2,6-bisphosphate is primarily made through isomeration of fructose 1,6-bisphosphate c. ATP is produced during glycolysis in a reaction catalyzed by enolase d. 1,3 bisphosphoglycerate is a substrate for a reaction which produces ATP in glycolysis
d. 1,3 bisphosphoglycerate is a substrate for a reaction which produces ATP in glycolysis
Please select the true statement:
a. Deficiency in porphobilinogen deaminase results in production of uroporphryinogen I b. Heme catabolism begins in the liver c. Pathologically high levels of conjugated bilirubin are indicative of anemia d. Chelation of the iron ion into protophorhyrin IX occurs in the mitochondrion e. None of the above is true
d. Chelation of the iron ion into protophorhyrin IX occurs in the mitochondrion
Enzyme A and B can use the same substrate. Enzyme A has a higher KM for the substrate than does Enzyme B. Which enzyme is more efficient in binding the substrate:
a. Enzyme A b. Enzyme B
b. Enzyme B
Please select the true statement:
a. The first committed step in heme synthesis is that catalyzed by a delta- aminolevulinate synthase b. Heme synthesis is regulated by the concentration of heme itself c. Heme is a prosthetic group that is found in both hemoglobin and myoglobin d. All of the above are true e. Only a and c are true
d. All of the above are true
The series of reactions carried out by the pyruvate dehydrogenase complex utilizes derivatives of all but which of the following:
a. Lipoic acid b. Niacin c. Pantothenic acid d. Riboflavin e. Folic acid f. Thiamine
e. Folic acid
Please select the true statement:
a. Under anaerobic conditions, regeneration of NAD+ is not possible b. Lactate dehydrogenase converts NAD+ to NADH to allow glycolysis to continue under conditions of insufficient oxygen partial pressure c. Pyruvate, once transported to the mitochondrion, can be used to make acetyl CoA for the TCA cycle, but cannot be used to make oxaloacetate for gluconeogenesis d. None of the above is true
d. None of the above is true
Please select the true statement:
a. 4 moles of ATP (net) are produced from one mole of glucose during glycolysis b. Regulation of fructose in glycolysis in the liver bypass both HK and PFK1 c. Fructose 1,6-bisphosphate has a higher phosphoric transfer potential than that of ATP d. None of the above is true
b. Regulation of fructose in glycolysis in the liver bypass both HK and PFK1
During glycolysis, phophoglucose isomerase converts a phospho-aldohexose to a phospho-ketohexose
a. True b. False
a. True
Please select the false statement:
a. Enzymes stabilize the transition state b. Enzymes increase the rate of the reaction c. Enzymes increase the amount of products made at equilibrium d. Enzymes may be protein or RNA or both
c. Enzymes increase the amount of products made at equilibrium
When glucose levels are low, PFK2 is activated
a. True b. False
b. False
Please select the true statement.
a. Fructose -1,6-bisphosphatase is a glycolytic enzyme b. Pyruvate carboxylase requires biotin to transfer activated CO2 to pyruvate to form malate c. Pyruvate carboxylase is a mitochondrial gluconeogenic enzyme that requires ATP d. Phosphoenol pyruvate carboxykinase requires GTP to form oxaloacetate
c. Pyruvate carboxylase is a mitochondrial gluconeogenic enzyme that requires ATP
Please select the true statement regarding glucose:
a. …. is an aldose b. …. is a C4 epimer of mannose c. …. in biosystems is in the L-configuration d. …. none of the above
a. …. is an aldose
Ketals and acetals are largely non-reactive groups, and do not open spontaneously.
a. True b. False
a. True
The free ΔG of many reactions in glycolysis are more favorable than ΔG° because in the cell, relative concentrations of products to reactants can make a reaction more favorable.
a. True b. False
a. True
Please select the following to make a true statement regarding carbonic anhydrase.
a. The zinc cofactor assists in catalysis by destabilizing a water molecule bound to it b. Histidines in the active assist catalysis by stabilizing the position of zinc and also abstracting a proton from water c. CO2 undergoes nucleophilic attack by OH- to form carbonic acid d. All of the above are true e. Only a and c are true
d. All of the above are true
Please identify the correct enzyme/mode of regulation of these glycolytic enzymes:
a. Phosphofructokinase 1 / Allosteric activation by fructose 1,6-bisphosphate b. Hexokinase / Inhibition by fructose 1,6-bisphosphate c. Phosphofructokinase 2 / Inhibition through phosphorylation d. Pyruvate kinase / Competitive inhibition by glucose 6-phosphate
c. Phosphofructokinase 2 / Inhibition through phosphorylation
Following production of phosphoenolpyruvate. ATP is synthesized in a substrate level phosphorylation of ADP catalyzed by pyruvate kinase.
a. True b. False
a. True
Please select the false statement:
a. cAMP binding to regulatory regions of protein kinase A (PKA) causes inactivation of PKA b. cAMP is made by adenylate cyclase c. Activation of the glucagon receptor causes increase in PKA activity d. PFK2 inactivation is a downstream result of PKA activation
a. cAMP binding to regulatory regions of protein kinase A (PKA) causes inactivation of PKA
Please select the correct inhibition / enzyme pair:
a. Fluoride ions / glyceraldehyde 3-phosphate dehydrogenase (GAPDH) b. Arsenic / pyruvate kinase (PK) c. Fluoride ions / enolase d. Arsenic / Hexokinase (HK)
c. Fluoride ions / enolase
Coenzyme A is a derivative of the B vitamin, pantothenic acid that can form high-energy thioester bonds to help catalyze the transfer of acyl groups.
a. True b. False
a. True
Which of the following increase PDC activity:
a. High ration of NAD+/NADH b. High concentration of ATP c. High concentration of acetyl CoA d. Phosphorylation by pyruvate dehydrogenase kinase
a. High ration of NAD+/NADH
Porphobiligen deaminase catalyzes synthesis of the linear tetrapyrrole in which 4 porphobiligen are condensed together and ammonium is released
a. True b. False
a. True
Solve for Vo when Km = 1 µM, [S] = 3 µM and Vmax = 0.001 mM/second
3/4
Please name the purpose for the active form of each vitamin:
a. Folic acid (folate) b. Niacin
a. Folic acid (folate) - carrier of one carbon groups such as methyl groups
b. Niacin - electron carrier
What type of reaction does aldolase catalyze during gluconeogenesis? Please write out the equation for the first committed step of heme synthesis - include the enzyme and all reactants and products
Glycine + succinyl CoA + H+ yields delta-aminolevulinate + CoA + CO2, and is synthesized by delta-aminolevulinate synthase
What type of reaction does aldolase catalyze during gluconeogenesis?
Aldol condensation, condensation, or lyase reaction
Please name the three enzymes in glycolysis that are irreversible The reaction catalyzed by malate dehydrogenase is:
HK
PFK1
PK
How many carbons are found in each of these metabolites:
a. Malate b. Pyruvate c. The acetyl group of acetyl CoA d. Dihydroxyacetone phosphate e. Oxaloacetate
a. Malate - 4
b. Pyruvate - 3
c. The acetyl group of acetyl CoA - 2
d. Dihydroxyacetone phosphate - 3
e. Oxaloacetate - 4
The reaction catalyzed by malate dehydrogenase is:
Malate + NAD+ yields oxaloacetate + NADH
Please select the true statement:
a. The first committed step in heme synthesis is a reaction catalyzed by the enzyme δ-aminolevulinate synthase b. The first committed step in heme synthesis is a condensation reaction between pyruvate and glycine c. The first committed step in heme synthesis is catalyzed by the enzyme porphobilinogen deaminase d. The first committed step in heme synthesis is regulated primarily by negative feedback in which the intermediate porphobilinogen inhibits the enzyme responsible for its synthesis
a. The first committed step in heme synthesis is a reaction catalyzed by the enzyme δ-aminolevulinate synthase
Please select the true statement:
a. Bilirubin, bound to serum albumin, is transported through the bloodstream from the liver to the intestines b. Conjugated bilirubin is transported through the bile duct to the gall bladder c. The final processes of heme catabolism are carried out by gut bacteria d. All the above are true e. Only b and c are true
a. Bilirubin, bound to serum albumin, is transported through the bloodstream from the liver to the intestines
Please select the true statement:
a. Increased conjugated bilirubin is a sign of anemia, neonatal jaundice or the resolution of a large bruise b. Synthesis of porphilinogen is deficient in acute intermittent porphyria c. The enzyme that inserts the iron ion into the center of the porphyrin ring of protoporphyrin IX, resulting in the formation of an active heme prosthetic group, is ferrochelatase d. In congenital porphyria, there is a build-up of the asymmetric ring, uroporphyrinogen III
c. The enzyme that inserts the iron ion into the center of the porphyrin ring of protoporphyrin IX, resulting in the formation of an active heme prosthetic group, is ferrochelatase
When an enzyme is added to a reaction, the relative concentration of products to reactants at equilibrium increases, as more products are made over a given time when an enzyme is present.
a. True b. False
b. False
Generally, enzymes increase the rate of a reaction by stabilizing the transition state.
a. True b. False
a. True
When glucose levels are low, the glycolytic pathway is activated.
a. True b. False
b. False
Prosthetic groups, like heme, are cofactors that are tightly held in their associated enzyme, whereas coenzymes, like NAD+, are loosely held cofactors.
a. True b. False
a. True
Please select the true statement:
a. ΔG is dependent on the difference in energy between the products and reactants b. ΔG is dependent on the energy path between the reactants and products c. When the ΔG > 0, the rate of the reaction in the forward direction will increase because the reaction is more favorable d. All of the above are true e. Only a and c are true
a. ΔG is dependent on the difference in energy between the products and reactants
Please select the true statement
a. Fructose-1,6-bisphosphate is a glycolytic intermediate that activates pyruvate kinase b. Fructose 6-phosphate inhibits hexokinase c. Enolase catalyzes a reaction in which phosphoenolpyruvate is used to produce ADP d. None of the above is true
a. Fructose-1,6-bisphosphate is a glycolytic intermediate that activates pyruvate kinase
Fructose-2,6-bisphosphate is an activator of the glycolytic enzyme phosphofructokinase I.
a. True b. False
a. True
Please choose the true statement:
a. The anomeric carbon in ketone sugars is carbon 1 b. Hemiketals are non-reducing and largely non-reactive c. Sucrose is a non-reducing disaccharide made up of glucose and fructose d. Lactose is a reducing disaccharides made up of galactose and fructose
c. Sucrose is a non-reducing disaccharide made up of glucose and fructose
Please choose the false statement
a. The active site of most enzymes takes up a small portion of the enzyme surface surface b. Enzymes bing to their substrates through a combination of many weak interactions c. Binding specificity of an enzyme for its substrate depends not he shape of active site and the amino acids localized there d. The Michaelis-Menten equation describes cooperative kinetics that can be represented by a sigmoidal curve
d. The Michaelis-Menten equation describes cooperative kinetics that can be represented by a sigmoidal curve
Km = Vmax/2
a. True b. False
b. False
Glucagon response in the liver results in which of the following?
a. Inhibition of gluconeogenesis b. Inhibition of phosphofructokinase 2 c. Activation of hexokinase d. Activation of phosphofructokinase 1
b. Inhibition of phosphofructokinase 2
Fructose entry in the liver bypasses phosphofructokinase I
a. True b. False
a. True
Please choose the true statement:
a. The pace of glycolysis is set by the enzyme hexokinase b. During gluconeogenesis, non-carbohydrate molecules like amino acids can be used as a carbon source for the synthesis of glucose c. Muscle cells release glucose in response to glucagon in order to supply the brain and red blood cells with this free glucose d. None of the above is above
b. During gluconeogenesis, non-carbohydrate molecules like amino acids can be used as a carbon source for the synthesis of glucose
Which of the metabolites below has a lower phosphoric transfer potential than ATP?
a. Creatine phosphate b. 1,3-bisphosphoglycerate c. Glycerol 3-phosphate d. Phosphoenolpyruvate
c. Glycerol 3-phosphate
Please choose the false statement:
a. In glycolysis, the enzyme that catalyzes the substrate phosphorylation of ADP to from ATP and pyruvate is pyruvate kinase b. Two enzymes that catalyze the first step of glycolysis is hexokinase and glucokinase c. Hexokinase is inhibited through negative feedback by its product, glucose 6-P d. Aldolase catalyzes an irreversible reaction, the cleaving of fructose 1,6-bisphosphate
d. Aldolase catalyzes an irreversible reaction, the cleaving of fructose 1,6-bisphosphate
The major purpose of the reaction catalyzed by lactate dehydrogenase is:
a. To produce oxygen for the muscles so that glycolysis can continue b. To produce NADH so that glycolysis may continue in the absence of oxygen c. To produce ADP so that glycolysis may continue in the absence of oxygen d. To produce ethanol e. To produce lactose f. There are no true answers here
f. There are no true answers here
The vitamin, folic acid is important for which of the following?
a. Electron transfer b. Nitrogen transfer c. Aldehyde transfer d. Single carbon transfer e. None of the above
d. Single carbon transfer
Please choose the false statement:
a. The pyruvate dehydrogenase complex catalyzes the oxidative decarboxylation of pyruvate to yield a 2-carbon group and CO2 b. The cofactor lipoamide is used by the pyruvate dehydrogenase complex to transfer an acetyl group to coenzyme A c. The pyruvate dehydrogenase complex uses FADH2 to oxidize dihydrolipoamide to reform the functional lipoamide and FAD d. To form lipoamide, lipoid acid is covalently linked to the 𝜺-amino group of a lysine in the PDC
c. The pyruvate dehydrogenase complex uses FADH2 to oxidize dihydrolipoamide to reform the functional lipoamide and FAD
Please choose the correct pair consisting of vitamin paired with its deficiency:
a. Vitamin A - scurvy b. Folic acid - neuronal tube defects c. Vitamin C - rickets d. Vitamin D - osteomalacia e. Only a, b, and d are true f. Only b and d are true
f. Only b and d are true
In the cori cycle, lactate produced in the muscles and red blood cells enters and travels in the bloodstream, to the liver, where the lactate is used to make glucose in the process of gluconeogenesis.
a. True b. False
a. True
Please choose the true statement:
a. Gluconeogenesis occurs primarily in the brain (~90%), and to a lesser degree in the red blood cells (~10%) b. Gluconeogenesis generally occurs when the cells need energy in the form of ATP c. The primary fuel of the brain and the sole fuel of erythrocytes is glucose d. Oxaloacetate enters the mitochondrion to be used to form pyruvate during gluconeogenesis
c. The primary fuel of the brain and the sole fuel of erythrocytes is glucose
The three reactions in glycolysis that cannot be reversed are catalyzed by which three enzymes?
a. Hexokinase, phosphofructokinase I, and aldolase b. Hexokinase, phosphofructokinase I, and phosphofructokinase 2 c. Hexokinase, phosphofructokinase I, and pyruvate kinase d. Phosphofructokinase I, phosphoenolpyruvate carboxykinase, and pyruvate carboxylase
c. Hexokinase, phosphofructokinase I, and pyruvate kinase
During galactose catabolism, galactose 1-P and UDP-glucose are used to yield UDP-galactose and glucose 1-P
a. True b. False
a. True
When blood sugar is low, which of the following is true:
a. Pyruvate kinase is phosphorylated and activated b. Fructose 2,6-bisphosphate 2 is activated c. Phosphofructokinase 2 is phosphorylated and activated d. The concentrations of fructose 2,6-bisphosphate are increased
b. Fructose 2,6-bisphosphate 2 is activated
Solve for Vo when Km = 1 µM, [S] = 3 µM and Vmax = 0.001mM/second
3/4
Please name two lipid soluble vitamins
A, D, E, K
Please write out the first committed step of glycolysis; remember to include all products and reactants.
F6P + ATP -> F1,6BP + ADP + H+ (catalyzed by PFK1)
Please state the enzyme deficient in acute intermittent porphyria
Phorphobilinogen deaminase
What effect does the following allosteric effector have on the enzyme listed beside it:
A) = activated, I = Inhibited, N) No effect
a. Citrate / phosphofructokinase I
b. AMP / fructose 1,6-bisphosphatase
c. Acetyl CoA / pyruvate carboxylase
d. ATP / pyruvate kinase
e. Fructose 1,6-bisphosphate / pyruvate kinase
a. Citrate / phosphofructokinase I
I
b. AMP / fructose 1,6-bisphosphatase
I
c. Acetyl CoA / pyruvate carboxylase
A
d. ATP / pyruvate kinase
I
e. Fructose 1,6-bisphosphate / pyruvate kinase
A
By what type of enzymatic process is UDP-galactose converted to UDP-glucose during the entry of galactose into glycolysis
Epimerization
Galactose is trapped in the cell by what enzyme?
Galactokinase
Galactokinase yields what products?
Galactose 1-P + ADP
