Final answer:
In glycolysis, fructose-6-phosphate's conversion to fructose-1,6-bisphosphate by phosphofructokinase is irreversible, serves as a key regulatory point, and indicates commitment to further metabolism leading to pyruvate and energy production. This step is regulated by ATP and ADP levels, inhibiting or activating the process, respectively.
Step-by-step explanation:
In the metabolic pathway known as glycolysis, the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate is a crucial regulatory step. This transformation is catalyzed by the enzyme phosphofructokinase and is fueled by the expenditure of one ATP molecule, which donates a phosphate group.
This particular step in glycolysis is not reversible and serves as a major point of control for the pathway. It is an example of end product inhibition, where an abundance of ATP indicates a reduction in the cell's need for energy, signaling phosphofructokinase to become less active. Conversely, high levels of ADP activate the enzyme, promoting the glycolytic pathway to generate more ATP.
Contrary to the statement that it is activated by ATP alone, the enzyme is actually inhibited by high levels of ATP. Once fructose-1,6-bisphosphate is formed, it is indeed committed to becoming two molecules of glyceraldehyde-3-phosphate, eventually leading to the production of pyruvate and the yield of energy through further enzymatic reactions.