Final answer:
Fructose 1-6 bisphosphate acts as an allosteric activator of pyruvate kinase, increasing its activity in the glycolysis pathway and promoting the production of pyruvate and ATP when energy is needed.
Step-by-step explanation:
When fructose 1-6 bisphosphate binds to pyruvate kinase, it acts as an allosteric activator of the enzyme. This binding increases the enzyme's activity as part of the glycolysis pathway. The last step of glycolysis, in which pyruvate is produced from phosphoenolpyruvate, is facilitated by this activation. If the demand for energy is low and the supply of alanine is sufficient, the activity of pyruvate kinase is inhibited to prevent unnecessary glucose breakdown. However, when fructose-1,6-bisphosphate levels are high, indicating that the cell requires more energy, it binds to pyruvate kinase and increases its activity, promoting the production of pyruvate and hence ATP. This regulation is a critical point in the metabolic control of energy production through glycolysis.