Gluconeogenesis must use "bypass reactions" to circumvent three reactions in the glycolytic pathway that are highly exergonic and essentially irreversible. Reactions carried out by which three of the enzymes listed must be bypassed in the gluconeogenic pathway?

1)Hexokinase

2)Phosphofructokinase (PFK)

3)Pyruvate kinase

Explanation:

The most important means of releasing energy from the glucose molecule is initiated by glycolysis.Glycolysis means splitting of the glucose molecule to form two molecules of pyruvic acid.The end products of glycolysis are then oxidized to provide energy.

Three reactions of glycolysis are highly exogernic,resulting in highly negative free energy changes that are irreversible and must be bypassed by different enzymes.These enzymes are hexokinase, Phosphofructokinase(PFK) and pyruvate kinase.

When the body's stores of carbohydrates decrease below normal,moderate quantities of glucose can be formed from amino acids and the glycerol portion of fat.This process is called gluconeogenesis. It is an important pathway that allows the body to store needed energy for the brain in the form if glucose.