Glycolysis is a fundamental metabolic pathway that breaks down glucose into pyruvate. It occurs in the cytoplasm of cells and does not require oxygen. This process is the first step in both aerobic and anaerobic respiration.
Overview of Glycolysis
Glycolysis involves the breakdown of a six-carbon glucose molecule into two molecules of pyruvate, a three-carbon molecule.
The process occurs in 10 steps, divided into two phases: the preparatory phase and the payoff phase.
- Preparatory phase: The first five steps utilize two ATP molecules. Glucose is phosphorylated, isomerized, phosphorylated again, split, and then isomerized one more time.
- Payoff phase: The next five steps involve the removal of phosphate groups and the production of high-energy complexes like ATP and NADH.
Glycolysis Pathway Stages
- Phosphorylation: A phosphate group is added to glucose, forming glucose-6-phosphate, with the help of hexokinase and ATP.
- Isomerization: Glucose-6-phosphate is isomerized into fructose-6-phosphate by phosphoglucoismerase.
- Phosphorylation: Another ATP molecule transfers a phosphate group to fructose-6-phosphate, converting it into fructose-1,6-bisphosphate, aided by phosphofructokinase.
- Cleavage: Fructose-1,6-bisphosphate is split into glyceraldehyde 3-phosphate (GAP) and dihydroxyacetone phosphate (DHAP) by aldolase.
- Isomerization: Triose-phosphate isomerase converts dihydroxyacetone phosphate into glyceraldehyde 3-phosphate.
- Oxidation and Phosphorylation: Glyceraldehyde 3-phosphate is oxidized and phosphorylated to 1,3-bisphosphoglycerate, producing NADH.
- ATP Production: 1,3-bisphosphoglycerate transfers a phosphate to ADP, forming ATP and 3-phosphoglycerate with the help of phosphoglycerokinase.
- Rearrangement: The phosphate of phosphoglycerate molecules is relocated from the third to the second carbon, yielding 2-phosphoglycerate by phosphoglyceromutase.
- Dehydration: Enolase removes a water molecule from 2-phosphoglycerate to form phosphoenolpyruvate.
- Pyruvate Formation: A phosphate from phosphoenolpyruvate is transferred to ADP to form pyruvate and ATP by pyruvate kinase.
Glycolysis is also known as the Embden-Meyerhof-Parnas pathway (EMP pathway), named after the scientists who discovered it. we offer several kits (both colorimetric and fluorometric) to analyze each of the products of this very central pathway.
