Regulation of Gluconeogenesis

Question 1

Describe the regulation of Gluconeogenesis

Answer 1

•Favoured by high [ATP] and low [AMP] or [ADP].

–Indicates plenty of energy is available.

• When energy is needed (high [AMP]) glycolysis is activated.
• When [ATP] is high and [AMP] is low, gluconeogenesis is activated.
• Essentially “stores” glucose.

Question 2

Gluconeogenesis: How is it favoured by availability of substrates for energy production in citric acid cycle?

Answer 2

–Citrate (citric acid cycle intermediate) inhibits phosphofructokinase.

–Acetyl CoA (feeds into citric acid cycle) stimulates pyruvate carboxylase.

Question 3

How is blood glucose regulated by Hormones?

Answer 3

• Insulin increases glycolysis.

–Released by pancreatic beta cells.

–In response to food intake and increase in blood glucose concentration.

• Glucagon decreases glycolysis.

–Released by pancreatic alpha cells.

–In response to decrease in blood glucose.

• Modulated by fructose 2,6-bisphosphate.

Question 4

Describe the formation of Fructose 2,6-bisphosphate

Answer 4

“Phosphofructokinase” is actually 6-phosphofructose-1-kinase.

F 1,6-BP in an intermediate of glycolysis and gluconeogenesis.

• Fructose 6-phosphate + ATP→ Fructose 1,6-bisphosphate

Likewise, 6-phosphofructose-2-kinase forms F 2,6-BP.

F 2,6-BP is a regulator of glycolysis and gluconeogenesis.

• Fructose 6-phosphate + ATP→ Fructose 2,6 bisphosphate

Question 5

Describe the Bifunctional Enzyme

Answer 5

• Both forms and degrades F 2,6-BP.
• Kinase domain phosphorylates (PFK).
• Phosphatase domain dephosphorylates (FBPase1).

Question 6

Draw a diagram of Glucagon Signalling

Answer 6