Glycolysis is a fundamental biochemical process that occurs in the cells of all organisms, from bacteria to humans. It is the first step in the breakdown of glucose to obtain energy in the form of ATP. Throughout the different stages of glycolysis, glucose is broken down into pyruvate, producing NADH and ATP in the process. This process is crucial for the production of energy in the form of ATP and for maintaining essential cellular functions.
The 10 phases of glycolysis
Phase 1: Glucose phosphorylation
Glycolysis begins with the phosphorylation of glucose, in which a glucose molecule is converted into glucose 6-phosphate thanks to the action of the enzyme hexokinase. This step requires energy from an ATP molecule, which is converted to ADP during the process.
Phase 2: Isomerization
In this stage, glucose 6-phosphate is converted into fructose 6-phosphate thanks to the action of the enzyme phosphohexose isomerase. This step is crucial to allow glucose to continue its breakdown in the following stages of glycolysis.
Phase 3: Fructose Phosphorylation
Fructose 6-phosphate is phosphorylated again to converted to fructose 1,6-bisphosphate, a step catalyzed by the enzyme phosphofructokinase. In this step, another ATP molecule is used to provide the energy needed for the reaction.
Phase 4: Cleavage of fructose 1,6-bisphosphate
Fructose 1,6- Biphosphate is split into two smaller molecules, dihydroxyacetone phosphate and glyceraldehyde 3-phosphate, thanks to the action of the enzyme aldolase. These two molecules will follow different metabolic pathways in the following stages of glycolysis.
Phase 5: Interconversion of dihydroxyacetone phosphate and glyceraldehyde 3-phosphate
Dihydroxyacetone phosphate is converted to glyceraldehyde 3- phosphate through the enzyme triose phosphate isomerase. This step is crucial to ensure that all the resulting molecules continue in the same metabolic pathway.
Phase 6: Generation of ATP and NADH
In this stage, glyceraldehyde 3-phosphate is breaks down to form phosphoglyceric acid, generating ATP and NADH in the process. This step is catalyzed by the enzyme glyceraldehyde 3-phosphate dehydrogenase, which plays a key role in energy production during glycolysis.
Phase 7: Creation of phosphoglycerate
Phosphoglyceric acid It is converted into 1,3-bisphosphoglycerate thanks to the action of phosphoglycerate kinase. In this step, an additional molecule of ATP is generated from ADP, contributing to the net production of ATP during glycolysis.
Phase 8: Creation of phosphoenolpyruvate
The 1,3-Bisphosphoglycerate is converted to phosphoenolpyruvate through the enzyme enolase, producing a water molecule in the process. This stage sets the stage for the final stage of glycolysis where the final product, pyruvate, is formed.
Phase 9: Generation of ATP
In this step, phosphoenolpyruvate is converted into pyruvate with the help of pyruvate kinase, generating a final ATP molecule from ADP. This is the last stage of glycolysis where energy is produced directly in the form of ATP.
Phase 10: Final production of pyruvate
Phosphoenolpyruvate is converted to pyruvate, which is a product key end of glycolysis. This pyruvate molecule is essential for many other metabolic pathways in the cell, including aerobic and anaerobic cellular respiration, where it will be converted to acetyl-CoA to continue the production of energy in the form of ATP.
In conclusion , glycolysis is a fundamental process in cellular metabolism that breaks down glucose to obtain energy in the form of ATP. Throughout the 10 phases of glycolysis, a series of enzymatic reactions are carried out that culminate in the production of ATP and pyruvate, essential for cellular function. Understanding the different stages of glycolysis is essential to appreciate the complexity and importance of this biochemical process in cellular energy production.