The malate/aspartate shuttle: if inhibited, could lead to the accumulation of cytosolic glyceraldehyde-3-phosphate within the ce

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The malate/aspartate shuttle: if inhibited, could lead to the accumulation of cytosolic glyceraldehyde-3-phosphate within the ce

ll (assume the glycerol-3-phosphate shuttle, LDH, and GNG are not found in this particular cell). if inhibited, would have little to no effect on the flux of GNG (gluconeogenesis). if inhibited, would result in the accumulation of cytosolic NAD (assume the glycerol-3-phosphate shuttle and GNG are not found in this particular cell). D) if inhibited, would result in the accumulation of cytosolic lactate (assume the glycerol-3-phosphate shuttle and GNG are not found in this particular cell). A) and D). A), B), and D). A), B), C), and D).

Biology

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vlada-n [2.5K] · Answer 1 · 2026-03-16T08:40:19+03:00

Answer: Keep in mind that the glycolytic pathway produces NADH in the cytosol during the oxidation of glyceraldehyde 3-phosphate, and regeneration of NAD+ is required for glycolysis to progress. How is NADH in the cytosol reoxidized when oxygen is present? NADH cannot directly enter the mitochondria to be oxidized by the respiratory chain, as the inner mitochondrial membrane doesn't allow NADH and NAD+ to pass. Instead, it is the electrons from NADH that are transported across the mitochondrial membrane. One way to introduce these electrons into the electron transport chain is through the glycerol 3-phosphate shuttle (refer to Figure 18.37). The initial step in this shuttle involves transferring a pair of electrons from NADH to dihydroxyacetone phosphate, which is an intermediate in glycolysis, resulting in the formation of glycerol 3-phosphate. This reaction is facilitated by a glycerol 3-phosphate dehydrogenase in the cytosol. Outside the inner mitochondrial membrane, glycerol 3-phosphate is reoxidized back to dihydroxyacetone phosphate by a membrane-bound isoform of glycerol 3-phosphate dehydrogenase. The electron pair moves from glycerol 3-phosphate to a FAD group in this particular enzyme, producing FADH2. This process also regenerates dihydroxyacetone phosphate.

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