SW 17

pyruvate kinase

Bisphosphoglycerate mutase deficiency is a rare inborn error of metabolism resulting in a reduction or absence of the enzyme in erythrocytes. Erythrocytes with a deficiency in both __________ and bisphosphoglycerate mutase would have 2,3-bisphosphoglycerate levels similar to that of unaffected erythrocytes. hexokinase aldolase pyruvate kinase phosphofructokinase

D. Hemoglobin oxygen saturation would be increased in the erythrocytes of individuals with bisphosphoglycerate mutase deficiency as compared to a normal individual.

Bisphosphoglycerate mutase deficiency is a rare inborn error of metabolism resulting in a reduction or absence of the enzyme in erythrocytes. How would the oxygen saturation of hemoglobin in an individual with bisphosphoglycerate mutase deficiency compare to that in an unaffected individual? Choose one: A. Hemoglobin oxygen saturation could be increased or decreased in the erythrocytes of individuals with bisphosphoglycerate mutase deficiency as compared to a normal individual. The effect of this deficiency would depend on glycolytic flux. B. Hemoglobin oxygen saturation would be decreased in the erythrocytes of individuals with bisphosphoglycerate mutase deficiency as compared to a normal individual. C. Hemoglobin oxygen saturation would be the same in the erythrocytes of individuals with bisphosphoglycerate mutase deficiency as compared to a normal individual. D. Hemoglobin oxygen saturation would be increased in the erythrocytes of individuals with bisphosphoglycerate mutase deficiency as compared to a normal individual.

A. aldolase

If phosphofructokinase experienced a mutation that interfered with substrate binding, then what other enzyme is going to be most immediately impacted in terms of accessing substrate? Choose one: A. aldolase B. fumarase C. glucolactonase D. hexokinase

B. In erythrocytes

In which situation is glycolysis alone likely to be a major contributor to ATP generation? Choose one: A. Under aerobic conditions B. In erythrocytes C. In liver cells D. In muscle cells

B. No, phosphate hydrolysis of glucose-6-phosphate is not spontaneous enough to couple to ATP synthesis.

Phosphorylation of glucose requires 1 ATP. Can the reverse reaction be used for substrate-level phosphorylation? Choose one: A. Yes, any reaction that involves ATP in either the forward or reverse direction is considered substrate-level phosphorylation. B. No, phosphate hydrolysis of glucose-6-phosphate is not spontaneous enough to couple to ATP synthesis. C. No, ATP is primarily produced through oxidative phosphorylation, and there is an insufficient amount of ADP available for substrate-level phosphorylation to occur. D. Yes, the breakdown of ATP in a metabolic reaction is always balanced with the synthesis of ATP in the reverse reaction.

B. to prevent hydrolysis of 1,3-bisphosphoglycerate.

Substrate binding to phosphoglycerate kinase induces a conformational change from an open to a closed complex. This conformational change is necessary to form a hydrophobic environment within the active site. A hydrophobic environment is necessary for optimal activity of phosphoglycerate kinase Choose one: A. for the positioning of the substrates within the active site. B. to prevent hydrolysis of 1,3-bisphosphoglycerate. C. to prevent early release of the substrates before the reaction is complete. D. for both substrates to bind to the active site.

C. 1,6-Dichloro-1,6-dideoxyfructose is a nonreducing sugar, and 4-chloro-4-deoxygalactose is a reducing sugar.

Sucralose is a nonnutrative sweetener composed of a chlorinated molecule shown below. The IUPAC name of this molecule is 1,6-dicholoro-1,6-dideoxy-β-D-fructofuranosyl-4-chloro-4-deoxy-α-D-galactopyranoside. Although the majority of ingested sucralose is not hydrolyzed in the small intestine, a small amount can be hydrolyzed to produce equimolar amounts of 1,6-dichloro-1,6-dideoxyfructose and 4-chloro-4-deoxygalactose. Are either of the hydrolysis products reducing sugars? Choose one: A. Both are reducing sugars. B. Both are nonreducing sugars. C. 1,6-Dichloro-1,6-dideoxyfructose is a nonreducing sugar, and 4-chloro-4-deoxygalactose is a reducing sugar. D. 1,6-Dichloro-1,6-dideoxyfructose is a reducing sugar, and 4-chloro-4-deoxygalactose is a nonreducing sugar.

B

The figure below shows two disaccharides commonly found in nature. Which end is responsible for a positive result in Benedict's test? Choose one: D B A C

C. -61.9 kJ/mol

The last reaction in glycolysis involves transfer of a phosphate group from phosphoenolpyruvate to ADP, yielding pyruvate and ATP. The coupled ΔG°' of this reaction is -31.4 kJ/mol. If ΔG°' of ATP hydrolysis is -30.5 kJ/mol, what is the ΔG°' of hydrolysis of phosphoenolpyruvate? Choose one: A. -92.4 kJ/mol B. 0.90 kJ/mol C. -61.9 kJ/mol D. -30.5 kJ/mol

B. The oxidation/reduction reaction is necessary to form an intermediate with a large free energy of hydrolysis.

The reaction mechanism of glyceraldehyde-3-phosphate dehydrogenase is shown below. Glyceraldehyde-3-phosphate dehydrogenase catalyzes the phosphorylation of glyceraldehyde-3-phosphate, but unlike other glycolytic reactions, it does not require energy investment from ATP. This reaction occurs in two stages: oxidation/reduction and phosphorylation. Why is the oxidation/reduction reaction necessary to make phosphorylation favorable? Choose one: A. The oxidation/reduction reaction is for the substrate to bind to the enzyme. B. The oxidation/reduction reaction is necessary to form an intermediate with a large free energy of hydrolysis. C. The oxidation/reduction reaction is necessary to oxidize phosphate, allowing addition to the substrate. D. The oxidation/reduction reaction is necessary to produce NADH, which is required for ATP synthesis.

(a)13.8 (b) -16.7

The standard free energy change of phosphate hydrolysis is shown below for several molecules in the glycolytic pathway. (a)Phosphorylation of glucose to produce glucose-6-phosphate has ΔG˚' = ______ kJ/mol without the use of ATP. (b) Coupling phosphorylation with ATP hydrolysis gives ΔG˚' = _____ kJ/mol. (a)0 (a)-13.8 (a)-29.7 (a)13.8 (b)-13.8 (b)-30.5 (b)-44.3 (b)-16.7

B. Without ATP investment, Q > Keq, and with ATP investment Q < Keq.

The standard free energy change of phosphate hydrolysis is shown below for several molecules in the glycolytic pathway. Using concentrations of intermediates found in a cell, the phosphorylation of glucose using inorganic phosphate has ΔG' = 19.7 kJ/mol, while phosphoryl transfer from ATP (ATP investment) results in ΔG' = -34.5 kJ/mol. What does this tell you about the values of Q and Keq for the phosphorylation of glucose with and without energy investment from ATP? Choose one: A. Without ATP investment, Q > Keq, and with ATP investment Q > Keq. B. Without ATP investment, Q > Keq, and with ATP investment Q < Keq. C. Without ATP investment, Q > Keq, and with ATP investment Q = Keq. D. Without ATP investment, Q < Keq, and with ATP investment Q > Keq.

C. Without ATP investment, one or both of the substrates would need to exceed the solvent capacity of the cell for glucose phosphorylation to occur.

The standard free energy change of phosphate hydrolysis is shown below for several molecules in the glycolytic pathway. Which statement explains why glucose phosphorylation could not occur without ATP investment? Choose one: A. Without ATP investment, glucose would not become "trapped" in the cell and could easily be transported out as blood glucose levels decrease. This transport would reduce the amount of glucose available for some organs. B. Without ATP investment it would be impossible to regulate the entry of glucose into glycolysis. C. Without ATP investment, one or both of the substrates would need to exceed the solvent capacity of the cell for glucose phosphorylation to occur. D. Without ATP investment in stage I of glycolysis, the concentration of ATP would become too high and would inhibit phosphofructokinase, leading to inhibition of the entire glycolytic pathway.

B

The structure of D-arabinose is shown below as a Fischer projection. Identify the correct structure of L-arabinose. A B C D

B. glucose isomerase

The two most common nutrative (caloric) sweeteners used in the manufacturing of food and beverages are sucrose and high-fructose corn syrup (HFCS). The latter is produced from corn syrup in a process that enzymatically converts a percentage of the glucose, which is the predominant sugar component, into fructose. HFCS used in most commercial food and beverage production is either 55% or 42% fructose. Which enzyme can be used in the production of HFCS to convert glucose to fructose in a single step? Choose one: A. glucose dehydrogenase B. glucose isomerase C. glucose oxidase D. glucose epimerase

A. HFCS is sweeter than corn syrup.

The two most common nutrative (caloric) sweeteners used in the manufacturing of food and beverages are sucrose and high-fructose corn syrup (HFCS). The latter is produced from corn syrup in a process that enzymatically converts a percentage of the glucose, which is the predominant sugar component, into fructose. HFCS used in most commercial food and beverage production is either 55% or 42% fructose. Why is HFCS preferred over corn syrup for sweetening beverages and processed foods? Choose one: A. HFCS is sweeter than corn syrup. B. HFCS is more natural than corn syrup. C. HFCS is less costly to produce than corn syrup. D. HFCS is less caloric than corn syrup.

A. A metal ion and ligand interact with the protein in locations proximal to one another.

Which of the following best describes the relationship among a subunit of the protein, metal cofactors, and ligands? Choose one: A. A metal ion and ligand interact with the protein in locations proximal to one another. B. Metal ions interact with one another within the protein at a distant location from the ligand interaction. C. Ligands interact with one another proximally within the protein at a distant location from the metal ion interaction. D. Metal ions and ligands interact with the protein in locations that are all quite distant from one another.

C. D-Ribose and D-Xylose are epimers

Which of the following relationships is correctly defined? Choose one: A. D-Glucose and D-Mannose are anomers B. D-Ribose and D-Xylose are isomers C. D-Ribose and D-Xylose are epimers D. D-Glucose and L-Glucose are anomers

A. Glucose can form furanose and pyranose ring structures, while fructose can only form a furanose ring. B. Glucose is found in at least three common disaccharides found in nature, while fructose is a component of only one. C. Glucose and fructose are both hexose sugars.

Which of the following statements correctly describe the properties of glucose and fructose? Choose one or more: A. Glucose can form furanose and pyranose ring structures, while fructose can only form a furanose ring. B. Glucose is found in at least three common disaccharides found in nature, while fructose is a component of only one. C. Glucose and fructose are both hexose sugars. D. Glucose and fructose are both reducing sugars.

A. Q < Keq for both reactions; Q/Keq uncoupled < Q/Keq coupled

under cellular conditions, ΔG' = -26.8 kJ/mol for the coupled reaction, while phosphoenolpyruvate hydrolysis has ΔG' = -76.0 kJ/mol. How does coupling phosphoenolpyruvate hydrolysis with ATP synthesis change the relationship between Q and Keq? Choose one: A. Q < Keq for both reactions; Q/Keq uncoupled < Q/Keq coupled B. Q > Keq for both reactions; Q/Keq uncoupled < Q/Keq coupled C. Q < Keq for both reactions; Q/Keq uncoupled > Q/Keq coupled D. Q > Keq for both reactions; Q/Keq uncoupled > Q/Keq coupled