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
