Harry was very thirsty: he accidentally drank a poison named DCCD to quench his

Question

Harry was very thirsty: he accidentally drank a poison named DCCD to quench his thirst. Now he is feeling exhausted and tired. He decides to lie down. Since you have studied cellular respiration in your biology class, Harry is hoping that you are able to determine where the problem is.

The facts at the cellular and molecular level:
- oxygen is present
- Harry is only producing 4 ATP molecules per molecule of glucose
- Pyruvate is present in the cytosol and Acetyl CoA is present in the mitochondria
- NADH and NAD+ are at normal levels.

Question: Considering the facts about Harry, where in the cellular respiration pathway does DCCD block? How do you know? Support your answer with evidence for full credit.

Explanation / Answer

Harry accidental drank the DCCD poison. DCCD is dicyclohexylcarbodimide. After consumption of it following conditions are seen at molecular level -  oxygen is present
- Harry is only producing 4 ATP molecules per molecule of glucose
- Pyruvate is present in the cytosol and Acetyl CoA is present in the mitochondria
- NADH and NAD+ are at normal levels.

From the above facts it is known that DCCD blocked the ATPase. It effects teh proton motive force across the plasma membrane of aerobic cells. ATPase is essential for the production of ATP. When it is inhibited the production of ATP is stopped. The transfer of protons do not take palce. So, the NADH and NAD+ are at normal levels. The 4 ATP molecules present are produced through glycolysis pathway. All the reations of the cellular respiration take place efficiently, but they are not converted to usable energy form of ATP, due to inhibition of ATPase. Evidence - It is can be proved that all othe rreactions of the cellular respiration are efficient. Like presence of oxygen, pyruvate in cytosol and acetyl CoA in mitochondria. Even the NADH and NAD+ are in normal levels. Here only the ATP levels are altered. Therefore we can predict that ATPAse is inhibited.

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