​Given below are a few statements regarding the rate of glycolysis, gluconeogenesis, and glycogen metabolism.

A. Increased blood glucose would decrease gluconeogenesis and increase glycogen synthesis.
B. Increased levels of fructose-1,6-bisphosphate inhibit glycolysis.
C. Increased blood glucagon inhibits glycogen synthesis and stimulates glycogen breakdown.
D. Increase in AMP levels inhibits glycolysis and stimulates gluconeogenesis.

Which one of the following options represents INCORRECT statements?

Correct option is B

Statement A: "Increased blood glucose would decrease gluconeogenesis and increase glycogen synthesis." - Correct

• When blood glucose levels are high, the body does not need to produce more glucose via gluconeogenesis, so gluconeogenesis is inhibited.
• Instead, excess glucose is stored as glycogen in the liver and muscles (glycogenesis).
• This regulation is mediated by insulin, which promotes glycogen synthesis while inhibiting gluconeogenesis.

Statement B: "Increased levels of fructose-1,6-bisphosphate inhibit glycolysis. - Incorrect

• Fructose-1,6-bisphosphate (F-1,6-BP) is an intermediate of glycolysis, NOT an inhibitor.
• In contrast, it stimulates glycolysis by activating pyruvate kinase, which enhances glucose breakdown for ATP production.
• Regulatory Mechanism:
  • A key enzyme in glycolysis, phosphofructokinase-1 (PFK-1), is activated by fructose-2,6-bisphosphate, which is different from fructose-1,6-bisphosphate.
  • The enzyme fructose-1,6-bisphosphatase (FBPase-1), which is involved in gluconeogenesis, is actually inhibited by fructose-2,6-bisphosphate.
• Thus, the statement is incorrect because F-1,6-BP does NOT inhibit glycolysis.

Statement C: "Increased blood glucagon inhibits glycogen synthesis and stimulates glycogen breakdown."  - Correct

• Glucagon is released when blood glucose levels are low, signaling the body to increase glucose availability.
• It inhibits glycogen synthesis (glycogenesis) and promotes glycogen breakdown (glycogenolysis) in the liver to release glucose into the bloodstream.
• Key Enzyme Regulation:
  • Glucagon activates glycogen phosphorylase, which breaks down glycogen.
  • Glucagon inhibits glycogen synthase, preventing further glycogen storage.

Statement D: "Increase in AMP levels inhibits glycolysis and stimulates gluconeogenesis - Incorrect

• AMP (adenosine monophosphate) is a key energy sensor in the cell.
• When ATP levels are low, AMP levels increase, signaling the need for more ATP production.
• AMP activates glycolysis (to generate ATP) and inhibits gluconeogenesis (which consumes ATP).
• Regulatory Mechanism:
  • AMP activates PFK-1, a key enzyme in glycolysis, increasing glucose breakdown.
  • AMP inhibits fructose-1,6-bisphosphatase (FBPase-1), suppressing gluconeogenesis.
• Thus, the statement is incorrect because AMP stimulates glycolysis and inhibits gluconeogenesis, not the other way around.