Glykolysen

Glycolysis is a metabolic pathway that occurs in the cytoplasm of cells and is the first step in the breakdown of glucose to produce energy. It is a series of ten enzymatic reactions that convert one molecule of glucose into two molecules of pyruvate, along with the production of ATP, NADH, and water. Glycolysis is a key component of cellular respiration and is present in all living organisms, from bacteria to humans.

The pathway can be divided into two phases: an energy investment phase and an energy payoff phase. In the energy investment phase, two molecules of ATP are consumed to phosphorylate glucose, forming glucose-6-phosphate. This is followed by the isomerization of glucose-6-phosphate to fructose-6-phosphate and the phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate. This step is catalyzed by phosphofructokinase-1, which is regulated by various factors, including ATP and AMP concentrations.

In the energy payoff phase, fructose-1,6-bisphosphate is split into two molecules of glyceraldehyde-3-phosphate, which are then oxidized to produce NADH and 1,3-bisphosphoglycerate. This is followed by the phosphorylation of 1,3-bisphosphoglycerate to 3-phosphoglycerate and the conversion of 3-phosphoglycerate to 2-phosphoglycerate. The final step is the conversion of 2-phosphoglycerate to pyruvate, which is accompanied by the release of ATP.

Glycolysis is a highly regulated pathway that is tightly controlled by various factors, including hormones, nutrients, and cellular energy status. It plays a crucial role in maintaining cellular homeostasis and is essential for the production of energy in the form of ATP. Additionally, glycolysis is a key pathway in the production of lactate during anaerobic conditions, which is used by cells to regenerate NAD+ for continued glycolysis.