Ch. 14

Question 1 of 23

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Glycolysis is the name given to a metabolic pathway occurring in many different cell types. It consists of 11 enzymatic steps that convert glucose to lactic acid. Glycolysis is an example of:

Select one of the following:

  • aerobic metabolism.

  • anabolic metabolism.

  • a net reductive process.

  • fermentation.

  • oxidative phosphorylation

Question 2 of 23

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The anaerobic conversion of 1 mol of glucose to 2 mol of lactate by fermentation is accompanied by a net gain of:

Select one of the following:

  • 1 mol of ATP.

  • 1 mol of NADH.

  • 2 mol of ATP.

  • 2 mol of NADH.

  • none of the above.

Question 3 of 23

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During strenuous exercise, the NADH formed in the glyceraldehyde 3-phosphate dehydrogenase reaction in skeletal muscle must be reoxidized to NAD+ if glycolysis is to continue. The most important reaction involved in the reoxidation of NADH is:

Select one of the following:

  • A) dihydroxyacetone phosphate → glycerol 3-phosphate
    B) glucose 6-phosphate → fructose 6-phosphate
    C) isocitrate → α-ketoglutarate
    D) oxaloacetate → malate
    E) pyruvate → lactate

  • dihydroxyacetone phosphate → glycerol 3-phosphate

  • glucose 6-phosphate → fructose 6-phosphate

  • isocitrate → α-ketoglutarate

  • oxaloacetate → malate

  • pyruvate → lactate

Question 4 of 23

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If glucose labeled with 14C in C-1 were fed to yeast carrying out the ethanol fermentation, where would the 14C label be in the products?

Select one of the following:

  • In C-1 of ethanol and CO2

  • In C-1 of ethanol only

  • In C-2 (methyl group) of ethanol only

  • In C-2 of ethanol and CO2

  • In CO2 only

Question 5 of 23

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The conversion of 1 mol of fructose 1,6-bisphosphate to 2 mol of pyruvate by the glycolytic pathway results in a net formation of:

Select one of the following:

  • 1 mol of NAD+ and 2 mol of ATP.

  • 1 mol of NADH and 1 mol of ATP.

  • 2 mol of NAD+ and 4 mol of ATP.

  • 2 mol of NADH and 2 mol of ATP.

  • 2 mol of NADH and 4 mol of ATP.

Question 6 of 23

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In an anaerobic muscle preparation, lactate formed from glucose labeled in C-3 and C-4 would be labeled in:

Select one of the following:

  • all three carbon atoms.

  • only the carbon atom carrying the OH.

  • only the carboxyl carbon atom.

  • only the methyl carbon atom.

  • the methyl and carboxyl carbon atoms.

Question 7 of 23

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Which of the following statements is not true concerning glycolysis in anaerobic muscle?

Select one of the following:

  • Fructose 1,6-bisphosphatase is one of the enzymes of the pathway.

  • It is an endergonic process.

  • It results in net synthesis of ATP.

  • It results in synthesis of NADH.

  • Its rate is slowed by a high [ATP]/[ADP] ratio.

Question 8 of 23

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When a muscle is stimulated to contract aerobically, less lactic acid is formed than when it contracts anaerobically because:

Select one of the following:

  • glycolysis does not occur to significant extent under aerobic conditions.

  • muscle is metabolically less active under aerobic than anaerobic conditions.

  • the lactic acid generated is rapidly incorporated into lipids under aerobic conditions.

  • under aerobic conditions in muscle, the major energy-yielding pathway is the pentose phosphate pathway, which does not produce lactate.

  • under aerobic conditions most of the pyruvate generated as a result of glycolysis is oxidized by the citric acid cycle rather than reduced to lactate.

Question 9 of 23

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Glycolysis in the erythrocyte produces pyruvate that is further metabolized to:

Select one of the following:

  • CO2.

  • ethanol.

  • glucose.

  • hemoglobin.

  • lactate.

Question 10 of 23

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When a mixture of glucose 6-phosphate and fructose 6-phosphate is incubated with the enzyme phosphohexose isomerase, the final mixture contains twice as much glucose 6-phosphate as fructose 6-phosphate. Which one of the following statements is most nearly correct, when applied to the reaction below (R = 8.315 J/mol·K and T = 298 K)?

Glucose 6-phosphate ↔ fructose 6-phosphate

Select one of the following:

  • ΔG'° is +1.7 kJ/mol.

  • ΔG'° is –1.7 kJ/mol.

  • ΔG'° is incalculably large and negative.

  • ΔG'° is incalculably large and positive.

  • ΔG'° is zero.

Question 11 of 23

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In glycolysis, fructose 1,6-bisphosphate is converted to two products with a standard free-energy change (ΔG'°) of 23.8 kJ/mol. Under what conditions (encountered in a normal cell) will the free-energy change (ΔG) be negative, enabling the reaction to proceed to the right?

Select one of the following:

  • If the concentrations of the two products are high relative to that of fructose 1,6-bisphosphate.

  • The reaction will not go to the right spontaneously under any conditions because the ΔG'° is positive.

  • Under standard conditions, enough energy is released to drive the reaction to the right.

  • When there is a high concentration of fructose 1,6-bisphosphate relative to the concentration of products.

  • When there is a high concentration of products relative to the concentration of fructose 1,6-bisphosphate.

Question 12 of 23

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Glucose labeled with 14C in C-1 and C-6 gives rise in glycolysis to pyruvate labeled in:

Select one of the following:

  • A and C.

  • all three carbons.

  • its carbonyl carbon.

  • its carboxyl carbon.

  • its methyl carbon.

Question 13 of 23

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If glucose labeled with 14C at C-1 (the aldehyde carbon) were metabolized in the liver, the first radioactive pyruvate formed would be labeled in:

Select one of the following:

  • all three carbons.

  • both A and C.

  • its carbonyl carbon.

  • its carboxyl carbon.

  • its methyl carbon.

Question 14 of 23

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In an anaerobic muscle preparation, lactate formed from glucose labeled in C-2 would be labeled in:

Select one of the following:

  • all three carbon atoms.

  • only the carbon atom carrying the OH.

  • only the carboxyl carbon atom.

  • only the methyl carbon atom.

  • the methyl and carboxyl carbon atoms.

Question 15 of 23

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If glucose labeled with 14C in C-3 is metabolized to lactate via fermentation, the lactate will contain 14C in:

Select one of the following:

  • all three carbon atoms.

  • only the carbon atom carrying the OH.

  • only the carboxyl carbon atom.

  • only the methyl carbon atom.

  • the methyl and carboxyl carbon atoms.

Question 16 of 23

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Which of these cofactors participates directly in most of the oxidation-reduction reactions in the fermentation of glucose to lactate?

Select one of the following:

  • ADP

  • ATP

  • FAD/FADH2

  • Glyceraldehyde 3-phosphate

  • NAD+/NADH

Question 17 of 23

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In comparison with the resting state, actively contracting human muscle tissue has a:

Select one of the following:

  • higher concentration of ATP.

  • higher rate of lactate formation.

  • lower consumption of glucose.

  • lower rate of consumption of oxygen

  • lower ratio of NADH to NAD+.

Question 18 of 23

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The steps of glycolysis between glyceraldehyde 3-phosphate and 3-phosphoglycerate involve all of the following except:

Select one of the following:

  • ATP synthesis.

  • catalysis by phosphoglycerate kinase.

  • oxidation of NADH to NAD+.

  • the formation of 1,3-bisphosphoglycerate.

  • utilization of Pi.

Question 19 of 23

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The first reaction in glycolysis that results in the formation of an energy-rich compound (i.e., a compound whose hydrolysis has a highly negative ΔG'°) is catalyzed by:

Select one of the following:

  • glyceraldehyde 3-phosphate dehydrogenase.

  • hexokinase.

  • phosphofructokinase-1.

  • phosphoglycerate kinase.

  • triose phosphate isomerase.

Question 20 of 23

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Which of the following is a cofactor in the reaction catalyzed by glyceraldehyde 3-phosphate dehydrogenase?

Select one of the following:

  • ATP

  • Cu2+

  • heme

  • NAD+

  • NADP+

Question 21 of 23

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In the phosphoglycerate mutase reaction, the side chain of which amino acid in the enzyme is transiently phosphorylated as part of the reaction?

Select one of the following:

  • serine

  • threonine

  • tyrosine

  • histidine

  • arginine

Question 22 of 23

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Inorganic fluoride inhibits enolase. In an anaerobic system that is metabolizing glucose as a substrate, which of the following compounds would you expect to increase in concentration following the addition of fluoride?

Select one of the following:

  • 2-phosphoglycerate

  • Glucose

  • Glyoxylate

  • Phosphoenolpyruvate

  • Pyruvate

Question 23 of 23

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Glycogen is converted to monosaccharide units by:

Select one of the following:

  • glucokinase.

  • glucose-6-phosphatase

  • glycogen phosphorylase.

  • glycogen synthase.

  • glycogenase.

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Quiz on Ch. 14, created by super_birdie on 21/08/2014.

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