Question

1. Predict what would happen to the concentrations of each of the following compounds (increase, decrease, no change), in the matrix of mitochondria, in the short term (a few minutes) after administration of a respiratory uncoupler such as 2,4-dinitrophenol. Provide a brief explanation for each.

1. 1. ATP:
2. 2. NAD⁺:

Answer 1

During electron transport chain proton are pumped from mitochondria matrix to the inner membrane space. This creates a proton gradient across the inner membrane. This proton gradient is utilized bt ATP synthase to synthesize ATP from ADP and Pi.

2,4-dinitrophenol disrupt the proton gradient by allowing proton present in the inner membrane space to mitochondria matrix. Thus, a proton is not available for ATP synthase and ATP synthesis is reduced.

So, ATP synthesis will be reduced and the concentration of ATP will be decreased.

NADH donates its electrons to complex I of the electrons transport chain and oxidize to NAD+. 2,4-dinitrophenol don't disrupt the electron transport chain. So, the level of NAD+ in the cells remains the same.

ATP: Level decreased

NAD+: Level remains the same.

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