Phosphofructokinase is an allosteric enzyme that catalyzes the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate, an early step of glycolysis. In the presence of oxygen, an increase in the amount of ATP in a cell would be expected to ________.
A) inhibit the enzyme and thus slow the rates of glycolysis and the citric acid cycle.
B) activate the enzyme and thus slow the rates of glycolysis and the citric acid cycle.
C) inhibit the enzyme and thus increase the rates of glycolysis and the citric acid cycle.
D) activate the enzyme and thus increase the rates of glycolysis and the citric acid cycle.
E) inhibit the enzyme and thus increase the rate of glycolysis and the concentration of citrate.

Question

Quizplus · Accepted Answer

Phosphofructokinase is inhibited by ATP, so an increase in ATP would lead to inhibition of the enzyme and a slowing of glycolysis and the citric acid cycle. This is a regulatory mechanism that helps prevent an excessive buildup of ATP in the cell.

Phosphofructokinase Is an Allosteric Enzyme That Catalyzes the Conversion of Fructose