gluconeogeneesille

Gluconeogenesis is a metabolic pathway that results in the generation of glucose from certain non-carbohydrate carbon substrates. This process occurs primarily in the liver and kidney cortex of vertebrates, and is a crucial mechanism for maintaining blood glucose levels when carbohydrate intake is low, such as during fasting or prolonged exercise.

The substrates for gluconeogenesis include lactate, pyruvate, glycerol, and glucogenic amino acids. These molecules are converted into pyruvate or enter the pathway at later stages. The process is essentially the reverse of glycolysis, but it involves several bypass reactions that overcome the irreversible steps of glycolysis. Key enzymes involved include pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose-1,6-bisphosphatase, and glucose-6-phosphatase.

Gluconeogenesis is an energy-consuming process, requiring ATP and GTP. It is tightly regulated by hormonal signals. Insulin generally inhibits gluconeogenesis, while glucagon and cortisol stimulate it, reflecting the body's need to mobilize glucose stores. This pathway plays a vital role in preventing hypoglycemia and ensuring adequate glucose supply to tissues like the brain, which rely heavily on glucose as their primary energy source. While essential for survival, excessive gluconeogenesis can contribute to hyperglycemia in conditions such as diabetes.