Glycolysis is the almost universal pathway that converts glucose into pyruvate along with the formation of nicotinamide adenine dinucleotide (NADH) and adenosine triphosphate (ATP). It primarily occurs in the cytoplasm of the cell.
Under aerobic conditions, the pyruvate passes into the mitochondria where it is completely oxidized by O2 into CO2 and H2O and its chemical energy largely conserved as ATP. Pyruvate generated via aerobic glycolysis feeds into the TCA or Krebs cycle.
In the absence of sufficient oxygen, the pyruvate is reduced by NADH via anaerobic glycolysis or fermentation to a wide range of products, routinely lactate in animals and ethanol in yeasts.
The starting molecule for glycolysis is glucose, a simple and abundant sugar found in carbohydrates, which provides the energy for most cells. Carbohydrates synthesized during photosynthesis act as the main storage molecules of solar energy. When ingested, complex carbohydrates are enzymatically hydrolyzed to monosaccharides, such as starch to D(+)-glucose.
The catabolism of glucose is the primary energy source for short-term requirements.
The remainder of this article will focus on the glycolytic pathway known as the Embden-Meyerhof-Parnas (EMP) pathway, named for its discoverers, Gustav Embden, Otto Meyerhof, and Jakub Karol Parnas. The chemical steps of the pathway are illustrated in the image to the right and via the video below.
The table below outlines the 10 individual reactions of the glycolytic pathway and the enzyme (with IUBMB Enzyme Commission number) that catalyzes each step.
Enzymes of Glycolysis
18.104.22.168 - Hexokinase
22.214.171.124 - Glucose-6-Phosphase Isomerase
126.96.36.199 - 6-Phosphofructokinase
188.8.131.52 - Fructose-bisphosphate aldolase
184.108.40.206 - Glyceraldehyde-3-phosphate dehydrogenase
220.127.116.11 - Phosphoglycerate kinase
18.104.22.168 - Phosphopyruvate hydratase (enolase)
22.214.171.124 - Pyruvate kinase
126.96.36.199 - Lactate dehydrogenase
This article has been expanded from its original form, published in BioFiles 2007, 2.6, 4.