Question

5. What is Gluconeogenesis? Where does it mainly take place in our body? Why does three exergonic steps in gluconeogenesis bypass in gluconeogenesis? Why gluconeogenesis is expensive? Why is it essential?

Answer 1

Gluconeogenesis - A metabolic process by which organisms produce sugars i,.e, glucose from non-carbohydrate precursors for the sake of essential catobolic processess is called gluconeogenesis.

This process i.e, gluconeogenesis occurs in the liver and kidneys.

There are a total of 10 reactions of gluconeogenesis , but out of these 10 only 7 is same with glycolysis.These reactions generally have change in Gibb's free energy ( ΔG) equal or close to zero.Hence easily reversible.But under intracellular conditions the value of  ΔG is found to be -63 KJ/mol in case of glycolysis while in case of gluconeogenesis , ΔG is -16 KJ/mol i.e, both pathways are irreversible.The irreversibility of the glycolytic pathway can be attributed to the fact that there is three exorgenic steps which are bypassed in gluconeogenesis.These exorgenic steps are bypassed with help of enzyme that catalyze irreversible steps to ensure the irreversibility of the metabolic pathway.

Gluconeogenesis is essential because :

• gluconogenesis ensures the maintenance of the appropriate blood glucose levels when the glycogen in the liver is almost depleted and no carbohydrates are ingested.
• Gluconogenesis is responsible for maintaining blood glucose within the normal range, 3.3 to 5.5 mmol/L (60 and 99 mg/dL) and  is essential because many cells and tissues depends largely on glucose to meet their ATP demands. Examples include red blood cells, neurons, skeletal muscle working under low oxygen conditions, the medulla of the kidney, the testes, the lens and the cornea of the eye.