Pyruvate kinase deficiency is associated with which metabolic pathway?

AIIMS CRE, SNO-2024

Biochemistry & Nutrition

Easy

Appeared in: AIIMS CRE, SNO-2024

Explanation

The Embden-Meyerhof pathway (EMP) is the scientific name for glycolysis, the central pathway for breaking down glucose to produce energy.
Pyruvate kinase is a key regulatory enzyme that catalyzes the final, irreversible step of glycolysis.
This crucial step involves converting phosphoenolpyruvate (PEP) to pyruvate, which also generates a molecule of ATP.
Therefore, a deficiency in the pyruvate kinase enzyme directly impairs the function of the Embden-Meyerhof pathway.

Option A: The Kreb's Cycle (or citric acid cycle) is a separate pathway that occurs in the mitochondria. It uses the product of glycolysis (pyruvate, after it's converted to Acetyl-CoA) but does not involve the enzyme pyruvate kinase itself.
Option C: The Pentose Phosphate Pathway (PPP) runs parallel to glycolysis but has different functions, primarily generating NADPH (for antioxidant defense) and precursor molecules for nucleotide synthesis. It does not involve pyruvate kinase.
Option D: Gluconeogenesis is the metabolic pathway for synthesizing glucose from non-carbohydrate precursors, making it largely the reverse of glycolysis. It must bypass the irreversible step catalyzed by pyruvate kinase, using different enzymes (pyruvate carboxylase and PEP carboxykinase) to do so.

Visual 1: Diagram: An overview of cellular metabolism, showing how Glycolysis (Embden-Meyerhof Pathway), Gluconeogenesis, the Kreb's Cycle, and the Pentose Phosphate Pathway are interconnected. The position of the enzyme Pyruvate Kinase at the final step of glycolysis should be clearly marked to illustrate its role.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Association of a specific enzyme deficiency (Pyruvate Kinase) with its corresponding metabolic pathway as background academic context rather than a clinical decision trigger.
Pyruvate kinase deficiency is the most common cause of congenital nonspherocytic hemolytic anemia. Nurses should be aware that this genetic disorder leads to insufficient ATP in red blood cells, causing them to become fragile and break down prematurely.
A key nursing consideration for patients with this condition is monitoring for signs of chronic hemolysis, such as jaundice (yellowing of the skin and eyes), fatigue, pallor, and an enlarged spleen (splenomegaly).
Patient education is vital, focusing on avoiding triggers that can worsen anemia, managing symptoms, and understanding the importance of regular follow-ups and potential treatments like blood transfusions or splenectomy.

How to Approach the Question

First, identify the key terms in the question: 'Pyruvate kinase deficiency' and 'metabolic pathway'. This tells you the question is linking a specific enzyme to its biochemical process.
Recall or deduce the function of pyruvate kinase. The name 'kinase' suggests it's involved in phosphate group transfer, often related to energy (ATP), and 'pyruvate' points to the end product of a major pathway.
Mentally review the main glucose metabolic pathways. Glycolysis breaks down glucose to pyruvate. The Kreb's cycle uses pyruvate's derivative. The Pentose Phosphate Pathway makes NADPH and ribose. Gluconeogenesis makes glucose.
Connect pyruvate kinase to its pathway. It is famously the enzyme for the final step of glycolysis.
Examine the options. 'Embden-Meyerhof pathway (EMP)' is the formal name for glycolysis. This is a direct match.
Confirm by eliminating the other options based on their distinct functions, ensuring they do not involve pyruvate kinase in the way described.

Concept Tested & Keywords

Concept Tested: Association of a specific enzyme deficiency (Pyruvate Kinase) with its corresponding metabolic pathway.
Stem keywords: Pyruvate kinase deficiency, metabolic pathway
Lead-in keywords: associated with

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