In: Chemistry
What two metabolic pathways are responsible foe endogenous glucose production.
Gluconeogenesis is the opposite process of glycolysis, which is the breakdown of glucose molecules into their components.
The process of gluconeogenesis is sometimes referred to endogenous glucose production (EGP) because it requires the input of energy.
Gluconeogenesis Pathway
1. Gluconeogenesis begins in either
the mitochondria or cytoplasm of the liver or kidney. First, two
pyruvate molecules are carboxylated to form oxaloacetate. One ATP
(energy) molecule is needed for this.
2. Oxaloacetate is reduced to malate by NADH so that it can be
transported out of the mitochondria.
Malate is oxidized back to oxaloacetate once it is out of the
mitochondria.
3. Oxaloacetate forms phosphoenolpyruvate using the enzyme
PEPCK.
4.Phosphoenolpyruvate is changed to fructose-1,6-biphosphate, and
then to fructose-6-phosphate. ATP is also used during this process,
which is essentially glycolysis in reverse.
5. Fructose-6-phosphate becomes glucose-6-phosphate with the enzyme
phosphoglucoisomerase.
6. Glucose is formed from glucose-6-phosphate in the cell’s
endoplasmic reticulum via the enzyme glucose-6-phosphatase. To form
glucose, a phosphate group is removed, and glucose-6-phosphate and
ATP becomes glucose and ADP.