Glycolysis and Gluconeogenesis Regulation

The video explains the regulation of glycolysis and gluconeogenesis through fructose 2,6-bisphosphate, a potent allosteric activator of phosphofructokinase-1 (PFK-1). It highlights the hormonal regulation by glucagon and insulin, which influence the levels of fructose 2,6-bisphosphate through a bifunctional enzyme. The phosphorylation state of this enzyme determines whether glycolysis or gluconeogenesis is favored. Real-world examples illustrate how these processes are controlled in response to different metabolic states.

What is the primary role of fructose 2,6-bisphosphate in glycolysis?

• It acts as a substrate for glycolysis.

• It activates phosphofructokinase-1.

• It is converted into glucose.

• It inhibits phosphofructokinase-1.

How does fructose 2,6-bisphosphate affect the affinity of PFK-1 for its inhibitors?

• It binds directly to ATP and citrate.

• It has no effect on the affinity.

• It increases the affinity for ATP and citrate.

• It decreases the affinity for ATP and citrate.

What is the effect of glucagon on cyclic AMP levels?

• It converts cyclic AMP into ATP.

• It increases cyclic AMP levels.

• It has no effect on cyclic AMP levels.

• It decreases cyclic AMP levels.

What happens to the bifunctional enzyme when cyclic AMP levels rise?

• It favors the phosphofructokinase-2 activity.

• It favors the fructose bisphosphatase-2 activity.

• It becomes inactive.

• It is degraded.

How does insulin affect the bifunctional enzyme involved in fructose 2,6-bisphosphate regulation?

• It inhibits the enzyme.

• It dephosphorylates the enzyme.

• It has no effect on the enzyme.

• It phosphorylates the enzyme.

What is the result of insulin activating phosphoprotein phosphatase?

• Increased levels of fructose 2,6-bisphosphate.

• Decreased levels of fructose 2,6-bisphosphate.

• Activation of gluconeogenesis.

• Inhibition of glycolysis.

In a fed state, what is the primary effect of insulin on glucose metabolism?

• It inhibits glycolysis.

• It stimulates gluconeogenesis.

• It converts glucose to glycogen.

• It stimulates glycolysis.

During fasting, which hormone is primarily responsible for stimulating gluconeogenesis?

• Adrenaline

• Cortisol

• Insulin

• Glucagon

What is the role of cyclic AMP in the regulation of glycolysis and gluconeogenesis?

• It directly activates glycolysis.

• It inhibits gluconeogenesis.

• It activates protein kinase.

• It is converted into glucose.

What is the ultimate control factor for glycolysis and gluconeogenesis?

• The liver

• The brain

• The kidneys

• The pancreas