Gluconeogenesis coverage check: which of the following processes is NOT excluded from gluconeogenesis (i.e., all listed processes actually participate in glucose formation)?

Difficulty: Medium

Correct Answer: None of the above (all are involved in gluconeogenesis)

Explanation:


Introduction / Context:
Gluconeogenesis is the anabolic pathway that synthesizes glucose from non-carbohydrate precursors such as lactate, glycerol, and glucogenic amino acids, primarily in the liver. This question tests recognition of processes that legitimately belong to gluconeogenesis.


Given Data / Assumptions:

  • Options list common steps or on-ramps associated with hepatic glucose production.
  • We interpret the stem under the Recovery-First Policy to clarify intent: identify whether any listed process is “not involved.”
  • If all listed processes are valid components, the appropriate answer is that none are excluded.


Concept / Approach:
Evaluate each option for its role in gluconeogenesis. Oxaloacetate conversion through phosphoenolpyruvate and up the pathway is central; lactate to pyruvate (via LDH) supplies carbon; glucose-6-phosphatase dephosphorylation is required to release free glucose into blood.


Step-by-Step Solution:
1) Option A: Oxaloacetate is converted to phosphoenolpyruvate (via PEPCK) and eventually to glucose—clearly involved.2) Option B: Lactate enters as pyruvate, a major Cori cycle substrate—clearly involved.3) Option C: Glucose-6-phosphatase removes phosphate from G6P in the endoplasmic reticulum, producing exportable glucose—clearly involved.4) Therefore, none of the listed processes is excluded; select “None of the above.”


Verification / Alternative check:
Standard hepatic gluconeogenesis outlines include LDH (lactate to pyruvate), PEPCK/OAA routing, and glucose-6-phosphatase as essential steps for completing glucose output.


Why Other Options Are Wrong:
Each named process is a textbook step in gluconeogenesis; declaring any single one as “not involved” would contradict pathway biochemistry. Option E (“all not involved”) is the opposite of reality.


Common Pitfalls:
Misreading the stem and selecting “all of the above” when the logic demands “none of the above,” or confusing glycolytic enzymes with the bypass steps specific to gluconeogenesis.


Final Answer:
None of the above (all are involved in gluconeogenesis)

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