Which are of the following is the correct sequence in Krebs cycle?
Correct answer: D. Isocitric acid → α-Ketoglutaric acid → Succinic acid
- A. Isocitric acid → Oxalosuccinic acid → α-Ketoglutaric acid
- B. Oxalosuccinic acid → Isocitric acid → α-Ketoglutaric acid
- C. α-Ketoglutaric acid → Isocitric acid → Oxalosuccinic acid
- D. Isocitric acid → α-Ketoglutaric acid → Succinic acid
Explanation
The correct sequence in the Krebs cycle is: Isocitric acid → α-Ketoglutaric acid → Succinic acid. During the cycle, isocitric acid undergoes oxidation and decarboxylation to form oxalosuccinic acid, a transient intermediate that quickly converts to α-ketoglutaric acid. α-Ketoglutaric acid then experiences oxidative decarboxylation, leading to the formation of succinyl-CoA, which is subsequently converted to succinic acid. The other options are incorrect as they either misorder the intermediates or inaccurately describe the chemical transformations that occur between these compounds.
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About Cellular Respiration
Cellular respiration releases energy from glucose through glycolysis, the link reaction, the Krebs cycle and the electron transport chain, producing ATP. The pathway differs in oxygen availability: aerobic respiration uses oxygen and yields more ATP, while anaerobic respiration produces much less ATP and forms lactic acid in muscles or ethanol and carbon dioxide in yeast.
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