The First Energy-Generating Steps in Glycolysis Begin When Glyceraldehyde 3-Phosphate

question 37

Multiple Choice

The first energy-generating steps in glycolysis begin when glyceraldehyde 3-phosphate undergoes an energetically favorable reaction in which it is simultaneously oxidized and phosphorylated by the enzyme glyceraldehyde 3-phosphate dehydrogenase to form 1,3-bisphosphoglycerate, with the accompanying conversion of NAD⁺ to NADH.In a second energetically favorable reaction catalyzed by a second enzyme, the 1,3-bisphosphoglycerate is then converted to 3-phosphoglycerate, with the accompanying conversion of ADP to ATP.Which of the following statements is TRUE about this reaction?

• A)The reaction glyceraldehyde 3-phosphate → 1,3-bisphosphoglycerate should be inhibited when levels of NADH fall.
• B)The ΔG° for the oxidation of the aldehyde group on glyceraldehyde 3-phosphate to form a carboxylic acid is more negative than the ΔG° for ATP hydrolysis.
• C)The energy stored in the phosphate bond of glyceraldehyde 3-phosphate contributes to driving the reaction forward.
• D)The cysteine side chain on the enzyme is oxidized by NAD⁺.

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