Question
Which of the following step is specific for gluconeogenesis
| A. |
Pyrovate to acetyl CoA
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| B. |
Oxaloacetate to citrate
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| C. |
Oxaloacetate to PEP
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| D. |
Conversion of 1,3-bisphosphoglycerate to glyceraldehyde-3-phosphate
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Show Answer
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Correct Answer » C
Explanation
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|
Ans. is ‘c’ i.e., Oxaloacetate to PEP
– Gluconeogenesis is the metabolic pathway generating glucose from non-carbohydrate precursors, mainly in liver and kidney cortex.
– It bypasses irreversible glycolytic steps to enable glucose synthesis during fasting or starvation.
Clinical Reasoning for the Correct Answer:
– Conversion of oxaloacetate to phosphoenolpyruvate (PEP) by PEP carboxykinase is a key gluconeogenesis-specific step.
– This step bypasses pyruvate kinase irreversible glycolytic step and allows glucose synthesis.
– Pyruvate is first converted to oxaloacetate by pyruvate carboxylase in mitochondria, then oxaloacetate is converted to PEP in cytosol or mitochondria.
– This critical reversal step highlights gluconeogenesis and does not occur in glycolysis.
