Which of the following regulatory mechanisms helps increase net glucose catabolism in the liver after a meal?

Question

Quizplus · Accepted Answer

11ecba2d_0e3b_3a82_a3bf_23fd72fd2daa_MD0008_00 Glucose uptake into cells and its subsequent metabolism are controlled primarily by the hormones insulin and glucagon. The binding of insulin and glucagon at the cell membrane stimulates or suppresses the biochemical pathways involved in the uptake, breakdown, and storage of glucose. Insulin stimulates glycolysis, which consists of a series of reactions that break down glucose into pyruvate to produce ATP. Glucagon acts in reverse by activating gluconeogenesis in the liver, which results in the synthesis of glucose from pyruvate and other precursor molecules. The well-fed state is characterized by the release of insulin in response to high levels of glucose in the blood. Insulin stimulates glucose catabolism (glycolysis) by activating synthesis of fructose-2,6-bisphosphate (F2,6BP). F2,6BP allosterically activates phosphofructokinase-1 (PFK-1), which catalyzes the rate-limiting step of glycolysis. In the liver, F2,6BP also inhibits fructose-1,6-bisphosphatase, which catalyzes the dephosphorylation of F1,6BP in gluconeogenesis. Inhibiting gluconeogenesis in the liver leads to increased net glucose catabolism. (Choice A) Hexokinase converts glucose into glucose-6-phosphate in the first step of glycolysis. Inhibition by glucose-6-phosphate would reduce glucose catabolism. (Choice B) Phosphofructokinase-1 catalyzes the conversion of fructose 6-phosphate to fructose-1,6-bisphosphate in glycolysis. Inhibiting this process with ATP would slow down glucose catabolism. (Choice C) Activation, not suppression, of F2,6BP synthesis increases glucose catabolism. Educational objective: Insulin stimulates glycolysis by activating the enzyme phosphofructokinase-2, which synthesizes fructose-2,6-bisphosphate. Fructose-2,6-bisphosphate allosterically activates phosphofructokinase-1 and inhibits fructose-1,6-bisphosphatase, which stimulates glycolysis and reduces gluconeogenesis.

Which of the Following Regulatory Mechanisms Helps Increase Net Glucose