Exam 2 Practice Exams

Question 1

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

Answer 1

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

Question 2

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

Answer 2

b. During gluconeogenesis, non-carbohydrates like amino acids can be used to ultimately synthesize the glucose

Question 3

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

Answer 3

c. Coenzyme A carries acyl groups by way of thirster formation

Question 4

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

Answer 4

a. The two enzymes that catalyze the first reaction of glycolysis are Hexokinase and Glucokinase

Question 5

FADH2 is oxidized to form FAD by means of hydride transfer to a substrate, and the substrate is thereby reduced.

a. True
b. False

Answer 5

b. False

Question 6

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

Answer 6

a.Porphobilinogen deaminase deficiency results in acute intermittent porphyria, which is caused by an increase in porphobilinogen and δ-aminolevulinate

Question 7

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

Answer 7

b. False

Question 8

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

Answer 8

e. All of the above are true

Question 9

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

Answer 9

c. Enzymes increase the amount of products made at equilibrium

Question 10

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

Answer 10

c. The pyruvate dehydrogenase complex is a mitochondrial complex that consists of multiple copies of E1, E2, and E3

Question 11

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

Answer 11

c. Ribose is a monosaccharide that is a pentose and an aldose

Question 12

Folic acid (folate) is important for fetal neural tube development

a. True
b. False

Answer 12

a. True

Question 13

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

Answer 13

b. A prosthetic group is a cofactor that is tightly bound to its enzyme whereas a coenzyme is loosely bound

Question 14

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

Answer 14

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

Question 15

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

Answer 15

b. Glucagon response in the liver results in inhibition of phosphofructokinase 2

Question 16

Flavin adenine dinucleotide is a vitamin derivative that participates in redox reactions

a. True
b. False

Answer 16

a. True

Question 17

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

Answer 17

f. Only a and c are true

Question 18

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

Answer 18

d. Enzymes function in many cases by stabilizing the transition state during a reaction

Question 19

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

Answer 19

b. Phosphoenolpyruvate carboxykinase, pyruvate carboxylase

Question 20

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

Answer 20

a. This enzyme functions in the mitochondrion and requires biotin

Question 21

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

Answer 21

a. True

Question 22

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

Answer 22

a. True

Question 23

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

Answer 23

c. During fructose catabolism in the muscle and liver, the enzyme phosphofructokinase 1 is bypassed

Question 24

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+

Answer 24

a. Anaerobic fermentation, to produce alcohol and NAD+, anaerobic production of lactate and NAD+, and aerobic oxidation in the electron transport chain

Question 25

Which three glycolytic enzymes catalyze regulated steps?

Answer 25

a. Hexokinase (HK) b. Phosphofructokinase (PFK or PFK1) c. Pyruvate kinase (PK)

Question 26

In a bifunctional enzyme that regulates glycolysis, which of these enzyme functionalities down regulates glycolysis?

Answer 26

Fructose Bisphosphatase

Question 27

Which glycolytic enzyme is regulated through feed-forward regulation?

Answer 27

PK by F1,6 BP

Question 28

Please write the first committed step of glycolysis. Be sure to include all reactants, products, and the enzyme catalyst.

Answer 28

F 6-P + ATP catalyzed by PFK1 and yielding F 1,6 BP + BP + ADP + H+

Question 29

List the five cofactors that are used in the pyruvate dehydrogenase complex

Answer 29

a. Thiamine pyrophosphate (TPP) b. Lipoamide c. Coenzyme A (CoA) d. FAD e. NAD+

Question 30

In what sub cellular compartment does heme synthesis begin and end?

Answer 30

Mitochondrion

Question 31

In what organ does heme degradation begin?

Answer 31

Spleen

Question 32

Please list the vitamin deficiency for each pathological condition: a. Osteomalacia b. Pellagra c. Beriberi d. Poor night vision e. Scurvy

Answer 32

a. Osteomalacia - vitamin D b. Pellagra - vitamin B2 (niacin) c. Beriberi - vitamin B1 (thiamine) d. Poor night vision - vitamin A e. Scurvy - vitamin C

Question 33

Please state the effect of a non-competitive inhibitor on: a. KM relative to KMapp b. Vmax relative to Vmaxapp

Answer 33

a. KM relative to KMapp = KM = KMapp | b. Vmax relative to Vmaxapp = Vmax > Vmaxapp

Question 34

The gluconeogenic enzyme fructose 1,6-bisphosphatase catalyzes a reaction that bypasses PFK1 a. True b. False

Answer 34

a. True

Question 35

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

Answer 35

b. One of the roles of the PDC is to produce the activated metabolite acetyl CoA

Question 36

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

Answer 36

b. The enzyme pyruvate kinase is allosterically activated by fructose 1,6-bisphosphate

Question 37

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

Answer 37

d. Enzymes lower the activation energy of a reaction by stabilizing the transition state

Question 38

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

Answer 38

d. To carry electrons transferred as hydrogen atoms

Question 39

The cofactor Coenzyme A is a derivative of which vitamin? a. Vitamin A b. Riboflavin c. Niacin d. Pantothenic acid e. Thiamin

Answer 39

d. Pantothenic acid

Question 40

Which of the vitamins is not water soluble? a. Vitamin A b. Riboflavin c. Niacin d. Pantothenic acid e. Thiamin

Answer 40

a. Vitamin A

Question 41

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

Answer 41

a. Lyase: ATP-dependent covalent bond cleavage

Question 42

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

Answer 42

c. Ribose is a pentose and an aldose

Question 43

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

Answer 43

a. δ-aminolevulinate synthase catalyzes a reaction that is the first and rate-limiting step in heme synthesis

Question 44

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

Answer 44

c. ….pyruvate carboxylase uses CO2 in oxaloacetate synthesis

Question 45

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

Answer 45

c. Bilirubin is a hydrophobic metabolite of heme degradation that is transported to the liver as bilirubin-digluconuronide

Question 46

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

Answer 46

a. ….binds substrates through many strong interactions

Question 47

Pyruvate contains 4 carbons; the acetyl group in acetyl CoA has 3 carbons. a. True b. False

Answer 47

b. False

Question 48

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

Answer 48

c. Coenzyme A carries acyl groups by way of thioester formation

Question 49

One of the hallmarks of non-competitive inhibitors is KM= KMapp, and Vmax is less than Vmaxapp. a. True b. False

Answer 49

b. False

Question 50

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

Answer 50

a. The two enzymes that catalyze the first reaction of glycolysis are hexokinase and glucokinase

Question 51

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

Answer 51

b. Isoenzymes are forms of an enzyme that may differ in regulation, kinetic parameters, location or time of expression

Question 52

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

Answer 52

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

Question 53

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+

Answer 53

b. ….pyruvate is a reactant and acetyl CoA is a product

Question 54

Vitamins are essential nutrients that are needed in trace amounts in the diet. a. True b. False

Answer 54

a. True

Question 55

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

Answer 55

d. All of the above are true

Question 56

Which of the following is caused by a defect in porphobilinogen deaminase? a. Acute intermittent porphyria b. Congenital erythropoietic porphyria c. Survy d. Beriberi

Answer 56

a. Acute intermittent porphyria

Question 57

The Michaelis-Menten constant Km is equal to 1/2 Vmax and is expressed in units of concentration sec-1 a. True b. False

Answer 57

b. False

Question 58

Please write the vitamin associated with this pathologic deficiency: a. Beriberi b. Neural tube defect

Answer 58

a. Beriberi - thiamine (B1) | b. Neural tube defect - Folic acid (folate, B9)

Question 59

Please state the enzyme that catalyzes the reaction that comes after the aldolase reaction in glycolysis:

Answer 59

Triose phosphate isomerase (TPI) / Glyceraldehyde 3 -P dehydrogenase

Question 60

Please write the reaction that is the first committed step in glycolysis and include the enzyme catalyst

Answer 60

F6P + ATP yields F1,6BP + ADP + H+ | PFKI catalyst

Question 61

Please name the two reactants of the first reaction in heme synthesis:

Answer 61

Succinyl CoA | Glycine

Question 62

Please name one condition for which high serum unconjugated bilirubin is an indicator

Answer 62

Resolution of a large hematoma, neonatal jaundice, anemia

Question 63

Please list the lipid soluble vitamins

Answer 63

Vitamin A, Vitamin D, Vitamin E, Vitamin K

Question 64

NADH is used as a source of electrons to reduce pyruvate during formation of lactic acid a. True b. False

Answer 64

a. True

Question 65

The reaction catalyzed by aldolase in glycolysis requires ATP a. True b. False

Answer 65

b. False

Question 66

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

Answer 66

e. None of the above is true

Question 67

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

Answer 67

e. None of the above are true

Question 68

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

Answer 68

c. RNA can act to catalyze reactions

Question 69

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

Answer 69

d. 1,3 bisphosphoglycerate is a substrate for a reaction which produces ATP in glycolysis

Question 70

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

Answer 70

d. Chelation of the iron ion into protophorhyrin IX occurs in the mitochondrion

Question 71

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

Answer 71

b. Enzyme B

Question 72

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

Answer 72

d. All of the above are true

Question 73

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

Answer 73

e. Folic acid

Question 74

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

Answer 74

d. None of the above is true

Question 75

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

Answer 75

b. Regulation of fructose in glycolysis in the liver bypass both HK and PFK1

Question 76

During glycolysis, phophoglucose isomerase converts a phospho-aldohexose to a phospho-ketohexose a. True b. False

Answer 76

a. True

Question 77

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

Answer 77

c. Enzymes increase the amount of products made at equilibrium

Question 78

When glucose levels are low, PFK2 is activated a. True b. False

Answer 78

b. False

Question 79

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

Answer 79

c. Pyruvate carboxylase is a mitochondrial gluconeogenic enzyme that requires ATP

Question 80

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

Answer 80

a. …. is an aldose

Question 81

Ketals and acetals are largely non-reactive groups, and do not open spontaneously. a. True b. False

Answer 81

a. True

Question 82

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

Answer 82

a. True

Question 83

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

Answer 83

d. All of the above are true

Question 84

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

Answer 84

c. Phosphofructokinase 2 / Inhibition through phosphorylation

Question 85

Following production of phosphoenolpyruvate. ATP is synthesized in a substrate level phosphorylation of ADP catalyzed by pyruvate kinase. a. True b. False

Answer 85

a. True

Question 86

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

Answer 86

a. cAMP binding to regulatory regions of protein kinase A (PKA) causes inactivation of PKA

Question 87

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)

Answer 87

c. Fluoride ions / enolase

Question 88

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

Answer 88

a. True

Question 89

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

Answer 89

a. High ration of NAD+/NADH

Question 90

Porphobiligen deaminase catalyzes synthesis of the linear tetrapyrrole in which 4 porphobiligen are condensed together and ammonium is released a. True b. False

Answer 90

a. True

Question 91

Solve for Vo when Km = 1 µM, [S] = 3 µM and Vmax = 0.001 mM/second

Answer 91

3/4

Question 92

Please name the purpose for the active form of each vitamin: a. Folic acid (folate) b. Niacin

Answer 92

a. Folic acid (folate) - carrier of one carbon groups such as methyl groups b. Niacin - electron carrier

Question 93

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

Answer 93

Glycine + succinyl CoA + H+ yields delta-aminolevulinate + CoA + CO2, and is synthesized by delta-aminolevulinate synthase

Question 94

What type of reaction does aldolase catalyze during gluconeogenesis?

Answer 94

Aldol condensation, condensation, or lyase reaction

Question 95

Please name the three enzymes in glycolysis that are irreversible The reaction catalyzed by malate dehydrogenase is:

Answer 95

HK PFK1 PK

Question 96

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

Answer 96

a. Malate - 4 b. Pyruvate - 3 c. The acetyl group of acetyl CoA - 2 d. Dihydroxyacetone phosphate - 3 e. Oxaloacetate - 4

Question 97

The reaction catalyzed by malate dehydrogenase is:

Answer 97

Malate + NAD+ yields oxaloacetate + NADH

Question 98

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

Answer 98

a. The first committed step in heme synthesis is a reaction catalyzed by the enzyme δ-aminolevulinate synthase

Question 99

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

Answer 99

a. Bilirubin, bound to serum albumin, is transported through the bloodstream from the liver to the intestines

Question 100

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

Answer 100

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

Question 101

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

Answer 101

b. False

Question 102

Generally, enzymes increase the rate of a reaction by stabilizing the transition state. a. True b. False

Answer 102

a. True

Question 103

When glucose levels are low, the glycolytic pathway is activated. a. True b. False

Answer 103

b. False

Question 104

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

Answer 104

a. True

Question 105

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

Answer 105

a. ΔG is dependent on the difference in energy between the products and reactants

Question 106

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

Answer 106

a. Fructose-1,6-bisphosphate is a glycolytic intermediate that activates pyruvate kinase

Question 107

Fructose-2,6-bisphosphate is an activator of the glycolytic enzyme phosphofructokinase I. a. True b. False

Answer 107

a. True

Question 108

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

Answer 108

c. Sucrose is a non-reducing disaccharide made up of glucose and fructose

Question 109

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

Answer 109

d. The Michaelis-Menten equation describes cooperative kinetics that can be represented by a sigmoidal curve

Question 110

Km = Vmax/2 a. True b. False

Answer 110

b. False

Question 111

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

Answer 111

b. Inhibition of phosphofructokinase 2

Question 112

Fructose entry in the liver bypasses phosphofructokinase I a. True b. False

Answer 112

a. True

Question 113

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

Answer 113

b. During gluconeogenesis, non-carbohydrate molecules like amino acids can be used as a carbon source for the synthesis of glucose

Question 114

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

Answer 114

c. Glycerol 3-phosphate

Question 115

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

Answer 115

d. Aldolase catalyzes an irreversible reaction, the cleaving of fructose 1,6-bisphosphate

Question 116

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

Answer 116

f. There are no true answers here

Question 117

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

Answer 117

d. Single carbon transfer

Question 118

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

Answer 118

c. The pyruvate dehydrogenase complex uses FADH2 to oxidize dihydrolipoamide to reform the functional lipoamide and FAD

Question 119

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

Answer 119

f. Only b and d are true

Question 120

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

Answer 120

a. True

Question 121

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

Answer 121

c. The primary fuel of the brain and the sole fuel of erythrocytes is glucose

Question 122

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

Answer 122

c. Hexokinase, phosphofructokinase I, and pyruvate kinase

Question 123

During galactose catabolism, galactose 1-P and UDP-glucose are used to yield UDP-galactose and glucose 1-P a. True b. False

Answer 123

a. True

Question 124

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

Answer 124

b. Fructose 2,6-bisphosphate 2 is activated

Question 125

Solve for Vo when Km = 1 µM, [S] = 3 µM and Vmax = 0.001mM/second

Answer 125

3/4

Question 126

Please name two lipid soluble vitamins

Answer 126

A, D, E, K

Question 127

Please write out the first committed step of glycolysis; remember to include all products and reactants.

Answer 127

F6P + ATP -> F1,6BP + ADP + H+ (catalyzed by PFK1)

Question 128

Please state the enzyme deficient in acute intermittent porphyria

Answer 128

Phorphobilinogen deaminase

Question 129

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

Answer 129

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

Question 130

By what type of enzymatic process is UDP-galactose converted to UDP-glucose during the entry of galactose into glycolysis

Answer 130

Epimerization

Question 131

Galactose is trapped in the cell by what enzyme?

Answer 131

Galactokinase

Question 132

Galactokinase yields what products?

Answer 132

Galactose 1-P + ADP