What are the irreversible steps of glycolysis?

The three irreversible steps of glycolysis occur at the following enzymes: 1) Hexokinase (or glucokinase in liver cells), which catalyzes the phosphorylation of glucose to glucose-6-phosphate. 2) Phosphofructokinase-1 (PFK-1), which converts fructose-6-phosphate to fructose-1,6-bisphosphate. 3) Pyruvate kinase, which converts phosphoenolpyruvate to pyruvate. These reactions are highly exergonic and cannot be reversed under normal physiological conditions.