Concept explainers
Figure 7.11 Dinitrophenol (DNP) is an "uncoupler" that makes the inner mitochondrial membrane "leaky" to protons. It was used until 1938 as a weight-loss drug. What effect would you expect DNP to have on the change in pH across the inner mitochondrial membrane? Why do you think this might be an effective weight-loss drug?
To write:
The effect of DNP on the pH across the mitochondrial membrane and the reason that it is a weight-loss drug.
Introduction:
Dinitrophenol (DNP) is an uncoupler. The flow of electrons can be separated by DNP along with the pumping of the H+ ion for the purpose of production of ATP (adenosine triphosphate). It means that the electron transport chain can no longer form a proton gradient, and ATP synthase can no longer make ATP.
DNP is a drug given to the patient for losing weight. After using DNA as weight loss drug, a person obtains less energy out of the eaten food. One of the worst side effects of taking DNP is overheating of the body, the energy from electron transport is lost as heat.
Explanation of Solution
DNP is an uncoupler, it disrupts the ATP synthesis by leaking protons across the inner mitochondrial membrane. As a result, the proton gradient cannot be formed across the inner mitochondrial membrane as pumping of H+ (hydrogen ion) is stopped. So, there will be a decrease in pH across the inner membrane of mitochondria.
Therefore, ATP production becoming less efficient. Hence, the energy which is normally produced during cellular respiration is being wasted as heat. In such condition, majority of the eaten food could not be used for the purpose of ATP synthesis and we lose weight.
DNP is an effective diet drug used to lose weight. It acts as an uncoupler which disrupts the H+ gradient across mitochondrial membrane reducing ATP synthesis. Since ATP cannot be formed, the energy from electron transport is lost as heat.
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Biology 2e
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