2. Glycolysis converts glucose to pyruvate by the following stoichiometry Glucos

Question

2. Glycolysis converts glucose to pyruvate by the following stoichiometry Glucose + 2ADP + 2Pi + 2NAD+ 2pyruvate + 2AIP + 2NADH + 2H+ + 2H201 Gluconeogenesis converts pyruvate to glucose by the following stoichiometry 2pyruvate +4ATP + 2GTP + 2NADH + 2H+ + 6H2Glucose + 4ADP + 2GDP + 6Pi + 2 NAD+ What is the net reaction when the glycolytic pathway and the gluconeogenic pathway are metabolically active at the same time? What does this tell you about the role of enzyme regulation in glycolysis and gluconeogenesis?

Explanation / Answer

During glycolysis, glucose will be converted to pyruvate, and during gluconeogenesis, pyruvate will be converted to glucose. So, if this occurs, thai is two metabolic pathways run in an opposite direction simultaneously, they will not show any overall effect except to dissipate energy in the heat form. So, if glycolysis and gluconeogenesis occurs at the same time, there will be an overall ATP consumption.

So, the overall reaction will be

ATP + H2O = ADP + Pi + Heat

So, ATP hydrolysis will occur without any useful metabolic work done. So, if these two reactions will proceed simultaneously in the same cell at a high rate, a huge number of chemical energy will dissipate as heat.

In glycolysis, fructose-6-phosphate is converted to fructose-1,6-bisphosphate in a reaction, which is catalysed by the enzyme phosphofructokinase (PFK-1).

ATP+ fructose-6-phosphate = ADP + Fructose-1,6-bisphosphate

But during gluconeogenesis, fructose-1,6-bisphosphate will be converted to fructose-6-phosphate.

Fructose-1,6-bisphosphate + H2O = fructose-6-phosphate + Pi

So, these may be very sensitive to small changes in the activity of enzymes, which are involved in the reaction.

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