Question

List the number of each step in glycolysis that must be bypassed during gluconeogenesis.

Answer 1

List the number of each step in glycolysis that must be bypassed during gluconeogenesis.

Solution:

There must be a way to bypass the irreversible steps in glycolysis to progress through gluconeogenesis. Generally, the bypass reactions are also irreversible.

There are three steps that need to be bypassed. We require four steps of gluconeogenesis to counteract those.

1. Phosphoenol Pyruvate to Pyruvate

Counteracted by -:

Pyruvate is converted to oxaloacetate (phosphoenolpyruvate) via pyruvate carboxylase.

Oxaloacetate is then converted to PEP by the enzyme PEPCK (phosphoenolpyruvate carboxykinase)


2. Fructose 6 Phosphate to Fructose 1,6 bisphosphate

Counteracted by enzyme FBPase. Fructose bisphosphate to Fructose 6 phosphate.

3. Glucose to Glucose 6 phosphate

Counteracted by another enzyme: G6Pase, which converts Glucose 6 phosphate to Glucose.