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arsenate is an analog of phosphate. it is a substrate for glyceraldehyde 3-phosp

ID: 220895 • Letter: A

Question

arsenate is an analog of phosphate. it is a substrate for glyceraldehyde 3-phosphate dehydrogenase (step 6 in glycolysis). The product of the reaction is the same as with phosphate (1,3-biphosphoglycerate). However, the intermediate is much more unstable and breaks down before ATP can be made.
What would the net effect of arsenate on the outputs of glycolysis: A) ATP B) NADH And C) pyruvate? arsenate is an analog of phosphate. it is a substrate for glyceraldehyde 3-phosphate dehydrogenase (step 6 in glycolysis). The product of the reaction is the same as with phosphate (1,3-biphosphoglycerate). However, the intermediate is much more unstable and breaks down before ATP can be made.
What would the net effect of arsenate on the outputs of glycolysis: A) ATP B) NADH And C) pyruvate? arsenate is an analog of phosphate. it is a substrate for glyceraldehyde 3-phosphate dehydrogenase (step 6 in glycolysis). The product of the reaction is the same as with phosphate (1,3-biphosphoglycerate). However, the intermediate is much more unstable and breaks down before ATP can be made.
What would the net effect of arsenate on the outputs of glycolysis: A) ATP B) NADH And C) pyruvate?

Explanation / Answer

Answer:

A. Net effect on ATP production:

Normally, 4 molecules of ATP are formed per glucose molecule; 2 ATP molecules at the conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate and 2 ATP molecules at the conversion of phosphoenolpyruvate to pyruvate. However, two molecules is ATP is spent; one at phosphorylation of glucose molecule and one at phosphorylation of fructose-6-phosphate.

If arsenate is present then the formation of 4 ATP molecules at the conversion of 1,3-biosphosphoglycerate to 3-phosphoglycerate halts and there will be no net ATP formation.

B. Effect on NADH production:

By bypassing the synthesis and phosphate transfer from 1,3-BPG, NADH production can be inhibited, thereby effecting the net energy production in glycolysis.

C. Effect on pyruvate output:

During arsenic poisoning in glycolysis, glycolysis continues to produce pyruvate but no net ATP is formed, because arsenate uncouples the substrate level phosphorylation by converting glyceraldehydes 3-phosphate into 3-phosphoglycerate without being converted to 1, 3 bisphosphoglycerate.