Glycolysis (Embden Meyerhof pathway)
Start with the big picture
Per glucose, glycolysis yields two pyruvate, two net ATP, and two NADH. The investment phase uses two ATP, while the pay-off phase generates four ATP through substrate-level phosphorylation. Three irreversible regulatory nodes are hexokinase or glucokinase, PFK-1, and pyruvate kinase; PFK-1 is the committed step and responds to cellular energy signals and fructose-2,6-bisphosphate. When oxygen is limited, conversion of pyruvate to lactate regenerates NAD⁺. In aerobic conditions, cytosolic NADH transfers its reducing equivalents into mitochondria through shuttles. The pathway also has clinical relevance: erythrocyte dependence on glycolysis helps explain the effects of pyruvate kinase deficiency, while fluoride inhibition of enolase is used to preserve blood glucose in laboratory samples.
What you'll learn
- Describe the overall glycolytic reaction and distinguish its investment and pay-off phases.
- Identify the irreversible steps and explain the regulatory role of PFK-1.
- Compare hexokinase and glucokinase using their kinetic and regulatory features.
- Explain how oxygen availability affects pyruvate fate and NAD⁺ regeneration.
- Relate glycolysis to erythrocyte energy needs and selected clinical applications.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
