363 - 461 Carbohydrate metabolism Flashcards
Which statement is true?
a. The carbon atoms of glucose and fatty acids are oxidized to CO2 in the body.
b. The electrons of fuel molecules are transferred to O2 by electron carriers.
c. Nutrient catabolism provides electrons for reductive biosynthesis.
d. Oxidative catabolism is driven by the high redox potential of molecular O2.
e. Fuel molecules can be oxidized by the removal of H atoms.
All correct
Which statement is true?
a. Oxidative catabolism is driven by the low redox potential of molecular O2.
b. Oxidative catabolism is driven by the high redox potential of molecular O2.
c. Nutrient catabolism provides electrons for reductive biosynthesis.
d. Fuel molecules can be oxidized by the addition of H atoms.
e. Fuel molecules can be oxidized by the removal of H atoms.
b. Oxidative catabolism is driven by the high redox potential of molecular O2.
c. Nutrient catabolism provides electrons for reductive biosynthesis.
e. Fuel molecules can be oxidized by the removal of H atoms.
Which statement is true regarding glycolysis?
a. It only evolved in higher eukaryotes (including humans).
b. The whole pathway takes place in the cytosol.
c. Its enzymes are present in all human cells.
d. Its first phase consumes 2 ATP per glucose molecules.
e. Its second phase yields 4 ATP and 4 NADH per glucose molecules.
b. The whole pathway takes place in the cytosol.
c. Its enzymes are present in all human cells.
d. Its first phase consumes 2 ATP per glucose molecules.
Which statement is true regarding glycolysis?
a. The whole pathway takes place in the cytosol.
b. The whole pathway is reversible.
c. Its second phase includes 2 kinase and 1 dehydrogenase enzymes.
d. Its first phase consumes 2 ATP per glucose molecules.
e. Its committed step is catalyzed by hexokinase or glucokinase
a. The whole pathway takes place in the cytosol.
c. Its second phase includes 2 kinase and 1 dehydrogenase enzymes.
d. Its first phase consumes 2 ATP per glucose molecules.
Which statement is false regarding glycolysis?
a. Its committed step is catalyzed by hexokinase or glucokinase.
b. The whole pathway takes place in the cytosol.
c. The whole pathway is reversible.
d. It only evolved in higher eukaryotes (including humans).
e. Its second phase yields 4 ATP and 2 NADH per glucose molecules.
a. Its committed step is catalyzed by hexokinase or glucokinase.
c. The whole pathway is reversible.
d. It only evolved in higher eukaryotes (including humans).
Which statement is true regarding the oxidative decarboxylation of pyruvate?
Select one or more:
a. It belongs to substrate level phosphorylation because an ATP is produced.
b. The whole process is catalyzed by an enzyme complex in the mitochondrial matrix.
c. Its enzymes are present in all human cells.
d. Human pyruvate decarboxylase contains biotin prosthetic group.
e. It yields NADH, which can deliver electrons to complex I of the respiratory chain.
b. The whole process is catalyzed by an enzyme complex in the mitochondrial matrix.
e. It yields NADH, which can deliver electrons to complex I of the respiratory chain.
Which statement is true regarding the oxidative decarboxylation of pyruvate in human cells?
Select one or more:
a. It cannot occur in anaerobic conditions.
b. It is catalyzed by an enzyme complex in the cytosol.
c. It is an irreversible reaction and it cannot be undone (i.e. pyruvate cannot be regenerated from the products).
d. It yields FADH2, which can deliver electrons to complex II of the respiratory chain.
e. It converts a glucoplastic to a ketoplastic molecule.
a. It cannot occur in anaerobic conditions.
c. It is an irreversible reaction and it cannot be undone (i.e. pyruvate cannot be regenerated from the products).
e. It converts a glucoplastic to a ketoplastic molecule.
Which statement is false regarding oxidative decarboxylation of pyruvate in human cells?
Select one or more:
a. It is an irreversible reaction but it can be undone (i.e. pyruvate can be regenerated from the products) by other enzymes.
b. It is catalyzed by a large enzyme complex (E1, E2 and E3) in the cytosol.
c. The process can occur in anaerobic conditions because the complex does not use O2.
d. It belongs to substrate level phosphorylation because an ATP is produced.
e. The prosthetic group of E1 is biotin, which is reoxidized by E3 in each catalytic cycle.
All correct
Which statement is false regarding oxidative decarboxylation of pyruvate in human cells?
Select one or more:
a. It is catalyzed by homodimers of pyruvate decarboxylase in the mitochondrial matrix.
b. The acetaldehyde intermediate is covalently bound to the enzyme as a hydroxyethyl group.
c. The product, acetate is bound to CoA in a macroergic thioester bond.
d. It is coupled to the mitochondrial electron transfer chain by NAD+ and NADH.
e. It is the last step of anaerobic glycolysis and it produces lactate
a. It is catalyzed by homodimers of pyruvate decarboxylase in the mitochondrial matrix.
e. It is the last step of anaerobic glycolysis and it produces lactate
Which statement is true?
Select one or more:
a. Oxidative phosphorylation is activated by ATP in starvation.
b. Oxidative catabolic processes in the mitochondrial matrix are coupled to respiration.
c. Citrate cycle is inhibited by high NADH/NAD+ ratio.
d. Pyruvate dehydrogenase is activated by low ATP/ADP ratio.
e. Malate/aspartate shuttle transports electrons from fatty acid oxidation to respiration.
b. Oxidative catabolic processes in the mitochondrial matrix are coupled to respiration.
c. Citrate cycle is inhibited by high NADH/NAD+ ratio.
d. Pyruvate dehydrogenase is activated by low ATP/ADP ratio.
Which statement is true?
Select one or more:
a. Citrate cycle cannot function in anaerobic conditions.
b. Fatty acid oxidation takes place in the cytosol.
c. Substrate level phosphorylation occurs both in glycolysis and in citrate cycle.
d. Uncouplers of oxidative phosphorylation cause inhibition of oxidative catabolism.
e. ADP activates oxidative phosphorylation as a substrate of FoF1 ATPase.
a. Citrate cycle cannot function in anaerobic conditions.
c. Substrate level phosphorylation occurs both in glycolysis and in citrate cycle.
e. ADP activates oxidative phosphorylation as a substrate of FoF1 ATPase.
Which statement is false?
Select one or more:
a. Substrate level phosphorylation occurs both in glycolysis and in citrate cycle.
b. Uncouplers of oxidative phosphorylation cause inhibition of oxidative catabolism.
c. Pyruvate dehydrogenase and citrate cycle cannot function in anaerobic conditions.
d. ADP activates oxidative phosphorylation as a substrate of FoF1 ATPase.
e. FoF1 ATPase is an active transporter, which can pump protons into the matrix.
b. Uncouplers of oxidative phosphorylation cause inhibition of oxidative catabolism.
e. FoF1 ATPase is an active transporter, which can pump protons into the matrix.
Which statement is false?
Select one or more:
a. Citrate cycle does not use O2, therefore it can function in anaerobic conditions.
b. Uncouplers of oxidative phosphorylation cause activation of oxidative catabolism.
c. Oxidative phosphorylation is uncoupled when the inner mitochondrial membrane is permeable for ions.
d. Respiration can be inhibited by KCN when oxidative phosphorylation is uncoupled.
e. Respiration can be inhibited by oligomycin when oxidative phosphorylation is uncoupled.
a. Citrate cycle does not use O2, therefore it can function in anaerobic conditions.
d. Respiration can be inhibited by KCN when oxidative phosphorylation is uncoupled.
Which is prosthetic group in pyruvate-dehydrogenase complex?
Select one or more:
a. flavine mononucleotide (FMN),
b. CoA,
c. thiamine pyrophosphate (TPP),
d. heme,
e. flavine adenine dinucleotide (FAD).
c. thiamine pyrophosphate (TPP),
e. flavine adenine dinucleotide (FAD).
Which cofactor is involved in the oxidative decarboxylation of pyruvate?
Select one or more:
a. CoA,
b. flavine mononucleotide (FMN),
c. CoQ,
d. NAD+,
e. biotine.
a. CoA,
d. NAD+,
Which enzyme contains FAD prosthetic group?
Select one or more:
a. α-ketoglutarate dehydrogenase complex,
b. E3 of PDH complex,
c. mitochondrial glycerol 3-phosphate dehydrogenase,
d. succinate dehydrogenase,
e. malate dehydrogenase.
a. α-ketoglutarate dehydrogenase complex,
b. E3 of PDH complex,
c. mitochondrial glycerol 3-phosphate dehydrogenase,
d. succinate dehydrogenase,
Which enzyme contains FAD prosthetic group?
Select one or more:
a. Complex I of the respiratory chain,
b. α -ketoglutarate dehydrogenase,
c. malate dehydrogenase,
d. pyruvate dehydrogenase complex,
e. isocitrate dehydrogenase.
b. α -ketoglutarate dehydrogenase,
d. pyruvate dehydrogenase complex,
Which enzyme uses NAD+/NADH?
Select one or more:
a. Complex I of the respiratory chain,
b. succinate dehydrogenase,
c. malate dehydrogenase,
d. acyl-CoA dehydrogenase,
e. glyceraldehyde 3-phosphate dehydrogenase.
a. Complex I of the respiratory chain,
c. malate dehydrogenase,
e. glyceraldehyde 3-phosphate dehydrogenase.
Which enzyme produces ATP in glycolysis?
Select one or more:
a. 3-Phosphoglycerate kinase,
b. Phosphofructokinase,
c. Hexokinase,
d. Pyruvate kinase,
e. Pyruvate dehydrogenase kinase.
a. 3-Phosphoglycerate kinase,
d. Pyruvate kinase,
Which enzyme consumes ATP in glycolysis?
Select one or more:
a. 3-Phosphoglycerate kinase,
b. phosphofructokinase,
c. hexokinase,
d. pyruvate kinase,
e. pyruvate dehydrogenase kinase.
b. phosphofructokinase, (produce B-1,6-F)
c. hexokinase, (produce G6P)
Which compound is allosteric activator for phosphofructokinase 1 (PFK1)?
Select one or more:
a. AMP,
b. citrate,
c. fructose 2,6-bisphosphate,
d. glucagon,
e. acyl-CoA.
a. AMP,
c. fructose 2,6-bisphosphate, (produced from F6P in a reaction catalyzed by PFK2)
Which compound is allosteric inhibitor for phosphofructokinase 1 (PFK1)?
Select one or more:
a. AMP,
b. citrate,
c. fructose 2,6-bisphosphate,
d. glucagon,
e. acyl-CoA.
b. citrate,
e. acyl-CoA.
Which activates pyruvate dehydrogenase complex?
Select one or more:
a. acetyl-CoA,
b. ATP,
c. ADP,
d. pyruvate dehydrogenase kinase,
e. Ca2+.
c. ADP,
e. Ca2+.
Which inhibits pyruvate dehydrogenase complex?
Select one or more:
a. CoA,
b. insulin,
c. ADP,
d. pyruvate dehydrogenase kinase,
e. NADH.
d. pyruvate dehydrogenase kinase,
e. NADH.
What is the right order of intermediates in glycolysis?
Select one or more:
a. 2-phosphoglycerate,
b. glyceraldehyde 3-phosphate,
c. dihydroxyacetone phosphate,
d. 3-phosphoglycerate,
e. 1-3-bisphosphoglycerate.
b. glyceraldehyde 3-phosphate,
c. dihydroxyacetone phosphate,
e. 1-3-bisphosphoglycerate.
d. 3-phosphoglycerate,
a. 2-phosphoglycerate,
What is the right order of intermediates in citrate cycle?
Select one or more:
a. succinyl-CoA,
b. fumarate,
c. succinate,
d. a-ketoglutarate,
e. malate.
d. a-ketoglutarate,
a. succinyl-CoA,
c. succinate,
b. fumarate,
e. malate.
What is the right order of electron carriers in the respiratory chain?
Select one or more:
a. cytochrome c,
b. succinate,
c. CuB,
d. ubiquinone,
e. FAD.
b. succinate,
e. FAD.
d. ubiquinone,
a. cytochrome c,
c. CuB,
(The ETC proteins in a general order are complex I, complex II, coenzyme Q, complex III, cytochrome C, and complex IV)
What is the right order of electron carriers in the respiratory chain?
Select one or more:
a. cytochrome c,
b. succinate,
c. CuB,
d. ubiquinone,
e. FAD.
b. succinate,
e. FAD.
d. ubiquinone,
a. cytochrome c,
c. CuB,
(The ETC proteins in a general order are complex I, complex II, coenzyme Q, complex III, cytochrome C, and complex IV)
What is the right order of electron carriers in the respiratory chain?
Select one or more:
a. cytochrome c,
b. FMN,
c. NADH,
d. CuB,
e. ubiquinone.
c. NADH,
b. FMN,
e. ubiquinone.
a. cytochrome c,
d. CuB,
Put these molecules in the decreasing order of phosphoryl group transfer potential.
Select one or more:
a. ATP,
b. 1-3-bisphosphoglycerate (phosphate on carbon
c. glucose 6-phosphate,
d. phosphoenolpyruvate,
e. phosphocreatine.
d. phosphoenolpyruvate,
b. 1-3-bisphosphoglycerate (phosphate on carbon
e. phosphocreatine.
a. ATP,
c. glucose 6-phosphate,
Which reactions can be enzymatically coupled to each other? (Eact: activation energy)
Select one:
a. one having high Eact and negative ΔG and one having high Eact and positive ΔG.
b. one having low Eact and negative ΔG and one having low Eact and positive ΔG.
c. one having high Eact and negative ΔG and one having low Eact and positive ΔG.
d. two reactions having low Eact and negative ΔG.
e. two reactions having high Eact and positive ΔG
c. one having high Eact and negative ΔG and one having low Eact and positive ΔG.
Which is the major role of lactate dehydrogenase (LDH) reaction in anaerobic glycolysis?
Select one:
a. production of ATP,
b. elimination of hydrogen,
c. elimination of lactate,
d. regeneration of NAD+,
e. regeneration of pyruvate.
d. regeneration of NAD+,
Which can be considered as the committed step of glycolysis?
Select one:
a. glyceraldehydes 3-phosphate dehydrogenase,
b. hexose phosphate isomerase,
c. hexokinase / glucokinase,
d. pyruvate kinase,
e. phosphofructokinase 1.
e. phosphofructokinase 1.
Which is not involved in oxidative decarboxylation of pyruvate by PDH complex?
Select one:
a. lipoamide,
b. biotin,
c. FAD,
d. CoA,
e. NAD+
b. biotin,
Which is not involved in oxidative decarboxylation of pyruvate by PDH complex?
Select one:
a. thiamine pyrophosphate,
b. FAD,
c. NAD+,
d. ubiquinone,
e. CoA.
d. ubiquinone,
Chose the correct/right sentence regarding hepatic phosphofructokinase1 (PFK1).
Select one:
a. Insulin increases fructose 2,6-bisphosphate level and hence activates PFK1.
b. Insulin decreases fructose 2,6-bisphosphate level and hence activates PFK1.
c. Insulin causes phosphorylation and activation of PFK1.
d. Glucagon causes phosphorylation and activation of PFK1.
e. Glucagon decreases fructose 2,6-bisphosphate level and hence activates PFK1.
b. Insulin decreases fructose 2,6-bisphosphate level and hence activates PFK1.
Chose the wrong/false sentence regarding hepatic phosphofructokinase (PFK) enzymes.
Select one:
a. Insulin causes dephosphorylation of PFK2 and activation of PFK1.
b. PFK2 uses ATP for irreversible phosphorylation of fructose 6-phosphate.
c. PFK1 is allosterically activated by AMP.
d. PFK1 is allosterically inhibited by citrate.
e. PFK1 is allosterically inhibited by fructose 2,6-bisphosphate.
e. PFK1 is allosterically inhibited by fructose 2,6-bisphosphate.
Chose the correct/right sentence regarding hepatic glycolysis.
Select one:
a. Hepatic glycolysis is activated in starvation for ATP production.
b. Hepatic glycolysis is inhibited by glucagon at two irreversible steps.
c. Hepatic glycolysis results in lactate production.
d. Hepatic glycolysis is activated when fructose 2,6-bisphosphate level decreases.
e. Hepatic glycolysis is inhibited when AMP level increases.
b. Hepatic glycolysis is inhibited by glucagon at two irreversible steps.
Chose the wrong/false sentence regarding hepatic phosphofructokinase (PFK) enzymes.
Select one:
a. Hepatic glycolysis is aerobic and it is followed by conversion of pyruvate to acetyl-CoA.
b. PFK-1 becomes activated if PFK-2 is dephosphorylated.
c. Hepatic glycolysis is inhibited when citrate level increases.
d. Hepatic glycolysis is activated in starvation by fructose 2,6-bisphosphate. e. Hepatic glycolysis is activated when AMP level increases.
a. Hepatic glycolysis is aerobic and it is followed by conversion of pyruvate to acetyl-CoA.
Chose the correct/right sentence (PDH: pyruvate dehydrogenase complex).
Select one:
a. Pyruvate activates PDH kinase and hence inhibits PDH.
b. Insulin activates PDH kinase and hence activates PDH.
c. ADP inhibits PDH kinase and hence activates PDH.
d. Ca2+ activates PDH phosphatase and hence inhibits PDH.
e. NADH activates PDH phosphatase and hence activates PDH.
c. ADP inhibits PDH kinase and hence activates PDH.
Identify the nucleotide built from the below ‘X’ isoalloxazine ring.
FAD
Identify the missing ‘X’ factor.
H+ + e-
Identify molecule ‘X’.
Semiquinone
Identify the missing ‘X’ factor.
H+ + e-
Identify the nucleotide built from the below ‘X’ isoalloxazine.
FADH2
Identify enzyme A!
Citrate synthase
Identify enzyme A!
Citrate synthase
421 Identify enzyme C!
Aconitase
422 Identify enzyme D!
Isocitrate dehydrogenase
423 Identify enzyme E!
Isocitrate dehydrogenase
423 Identify enzyme F
𝛂-ketoglutarate dehydrogenase complex
423 Identify enzyme G
Succinate thiokinase
423 Identify enzyme I!
Fumarase
423 Identify enzyme J!
Malate dehydrogenase
Identify Cofactor A!
NAD+/NADH+H+
Identify Cofactor B!
NAD+/NADH+H+
Identify Cofactor C!
ATP/ ADP + Pi
Identify Cofactor D!
FAD/ FADH2
Identify Cofactor E!
NAD+/NADH+H+
Identify substrate A
Identify substrate A
Identify substrate B
Citrate
Identify substrate C
Cis-anconitate
Identify substrate D
Isocitrate
Identify substrate E
Oxalosuccinate
Identify substrate F
α-Ketoglutarate
Identify substrate G
Succinyl-CoA
Identify enzyme A!
Transaminase
Identify enzyme E!
Transaminase
Identify enzyme D!
Transaminase
Identify enzyme C!
Pyruvate carboxylase
Identify enzyme B!
Phosphoenol pyruvate carboxykinase
Identify enzyme A!
Pyruvate dehydrogenase
Identify enzyme D!
Citrate lyase
Identify enzyme E!
Malate dehydrogenase
Identify enzyme F!
Malic enzyme
Identify enzyme E!
Citrate synthase
Identify enzyme C!
Pyruvate carboxylase
Identify substrate A
Pyruvate
Identify substrate C
Oxaloacetate
Identify substrate D
Citrate
Identify substrate E
Pyruvate
Identify substrate F
Malate
Identify substrate G
Oxaloacetate
