Arsenate Is a Toxic Ion That Can Interfere with Both

question 7

Multiple Choice

Arsenate is a toxic ion that can interfere with both glycolysis and oxidative phosphorylation. Arsenate resembles Pᵢ (inorganic phosphate) and can replace it in many enzymatic reactions. One such reaction is catalyzed by glyceraldehyde 3-phosphate dehydrogenase in step 6 of glycolysis. Upon completion of the reaction, instead of the normal product, 1,3-bisphosphoglycerate, the mixed anhydride 1-arsenato-3-phosphoglycerate is formed; this undergoes rapid spontaneous hydrolysis into arsenate plus 3-phosphoglycerate, the latter being a normal product of step 7 in glycolysis. What would be the effect of arsenate poisoning in glycolysis?

• A) It results in more ATP and NADH molecules generated for every glucose molecule.
• B) It results in fewer ATP molecules generated per glucose molecule, but NADH generation is not directly affected.
• C) It brings glycolysis to an abrupt stop.
• D) It results in fewer ATP and NADH molecules generated per glucose molecule.
• E) It does not affect the number of ATP or NADH molecules generated per glucose molecule.

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