Question:medium
Gluconeogenesis from lactate needs all of the following except?
Gluconeogenesis from lactate needs all of the following except?
Show Hint
Cori cycle uses lactate to pyruvate to glucose; pyruvate to alanine is the glucose-alanine cycle.
Updated On: Jun 24, 2026
- Transport of lactate from muscle to liver
- Conversion of lactate to pyruvate
- Transamination of pyruvate to alanine
- None of the above
Show Solution
The Correct Option is C
Solution and Explanation
Step 1: The stem asks which listed event does not belong to lactate-driven gluconeogenesis, so we look for the odd one out.
Step 2: Picture the Cori cycle. Muscle pours out lactate during heavy work; the bloodstream ferries it to the liver. That carriage step is essential, so option a stays in.
Step 3: Once inside hepatocytes, lactate dehydrogenase oxidises lactate to pyruvate. Pyruvate is the true entry molecule for the gluconeogenic pathway, so option b is also a genuine requirement.
Step 4: Turning pyruvate into alanine by transamination is the hallmark of the glucose-alanine (Cahill) cycle, a separate nitrogen-shuttling route. It actually pulls pyruvate out of the glucose-making line, so it is the step that is NOT needed here.
\[\boxed{\text{Transamination of pyruvate to alanine}}\]
Step 2: Picture the Cori cycle. Muscle pours out lactate during heavy work; the bloodstream ferries it to the liver. That carriage step is essential, so option a stays in.
Step 3: Once inside hepatocytes, lactate dehydrogenase oxidises lactate to pyruvate. Pyruvate is the true entry molecule for the gluconeogenic pathway, so option b is also a genuine requirement.
Step 4: Turning pyruvate into alanine by transamination is the hallmark of the glucose-alanine (Cahill) cycle, a separate nitrogen-shuttling route. It actually pulls pyruvate out of the glucose-making line, so it is the step that is NOT needed here.
\[\boxed{\text{Transamination of pyruvate to alanine}}\]
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