Question

In mitochondria, the rate of electron transfer is tightly coupled to the demand for ATP. When the rate of use of ATP is relatively low, the rate of electron transfer is low; when demand for ATP increases, electron‑transfer rate increases. Under these conditions of tight coupling, the number of ATP molecules produced per atom of oxygen consumed when NADH is the electron donor, the P/O ratio, is about 2.5. Predict what would happen when an uncoupling agent, such as 2,4‑dinitrophenol, is added to an actively respiring tissue preparation. The rate of oxygen consumption

Answer 1

Answer:

The correct answer will be- P/O decreases

Explanation:

The uncoupling agents are the chemical drugs which uncouple the two different process of cellular respiration which is the electron transport chain from the oxidative phosphorylation or ATP synthesis.

The synthesis of one ATP requires two electrons on the basis of which ATP production/ oxygen atom or P/O ratio is calculated.

When 2,4‑dinitrophenol uncouples the ATP synthesis from electron transport chain, then demand of oxygen for the synthesis of ATP increases which result in the decrease in the value of the P/O ratio.

Thus, P/O decreases are the correct answer.

Answer 2

Mitochondria is the cell organelle where the electron transport chain occurs and is a series of complexes. An increase in the rate of oxygen consumption decreases the P/O ratio.

What is the ETC of the mitochondria?

The electron transport chain is a sequence of complexes that occurs in the membrane of the mitochondria and is a redox reaction. This chain results in the formation of an energy molecule called ATP.

Some of the chemical drugs act as the uncoupling agent and uncouples the molecules of the cellular respiration cycles, including the ETC from the oxidative phosphorylation or the synthesis process of the ATP.

The ratio of the P/O is calculated based on the amount of ATP generated as two electrons results in the formation of one ATP molecule.

The uncoupling agent like 2,4‑dinitrophenol uncouple the synthesis of the ATP molecule from the ETC and increases the demand of the oxygen molecules for the ATP synthesis resulting in the decrease of the P/O ratio.

Therefore, the P/O ratio decreases.

Learn more about ETC here:

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