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Glycolysis is a metabolic pathway that converts glucose into pyruvate, generating ATP and NADH. This process occurs in the cytoplasm of cells.

10 Steps of Glycolysis
  1. Phosphorylation of Glucose: Glucose is phosphorylated by ATP to form glucose-6-phosphate. (Glucose+ATP→Glucose−6−phosphate+ADP)(Glucose + ATP \rightarrow Glucose-6-phosphate + ADP)
  2. Isomerization of Glucose-6-phosphate: Glucose-6-phosphate is isomerized to fructose-6-phosphate. (Glucose−6−phosphate↔Fructose−6−phosphate)(Glucose-6-phosphate \leftrightarrow Fructose-6-phosphate)
  3. Phosphorylation of Fructose-6-phosphate: Fructose-6-phosphate is phosphorylated by ATP to form fructose-1,6-bisphosphate. (Fructose−6−phosphate+ATP→Fructose−1,6−bisphosphate+ADP)(Fructose-6-phosphate + ATP \rightarrow Fructose-1,6-bisphosphate + ADP)
  4. Cleavage of Fructose-1,6-bisphosphate: Fructose-1,6-bisphosphate is cleaved into two 3-carbon sugars: dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (GAP). (Fructose−1,6−bisphosphate↔DHAP+GAP)(Fructose-1,6-bisphosphate \leftrightarrow DHAP + GAP)
  5. Isomerization of DHAP: Dihydroxyacetone phosphate is isomerized to glyceraldehyde-3-phosphate, so that two molecules of GAP can proceed through the rest of the pathway. (DHAP↔GAP)(DHAP \leftrightarrow GAP)
  6. Oxidation and Phosphorylation of Glyceraldehyde-3-phosphate: Glyceraldehyde-3-phosphate is oxidized and phosphorylated to 1,3-bisphosphoglycerate, generating NADH. (GAP+NAD++Pi↔1,3−bisphosphoglycerate+NADH+H+)(GAP + NAD^+ + P_i \leftrightarrow 1,3-bisphosphoglycerate + NADH + H^+)
  7. Substrate-Level Phosphorylation: The phosphate group from 1,3-bisphosphoglycerate is transferred to ADP, forming ATP and 3-phosphoglycerate. (1,3−bisphosphoglycerate+ADP↔3−phosphoglycerate+ATP)(1,3-bisphosphoglycerate + ADP \leftrightarrow 3-phosphoglycerate + ATP)
  8. Isomerization of 3-Phosphoglycerate: 3-phosphoglycerate is isomerized to 2-phosphoglycerate. (3−phosphoglycerate↔2−phosphoglycerate)(3-phosphoglycerate \leftrightarrow 2-phosphoglycerate)
  9. Dehydration of 2-Phosphoglycerate: 2-phosphoglycerate is dehydrated to form phosphoenolpyruvate (PEP). (2−phosphoglycerate↔PEP+H2O)(2-phosphoglycerate \leftrightarrow PEP + H_2O)
  10. Second Substrate-Level Phosphorylation: The phosphate group from phosphoenolpyruvate is transferred to ADP, forming ATP and pyruvate. (PEP+ADP→Pyruvate+ATP)(PEP + ADP \rightarrow Pyruvate + ATP)
Enzymes Controlling Each Step of Glycolysis
  1. Step 1: Hexokinase (or Glucokinase in liver/pancreas)
  2. Step 2: Phosphoglucose Isomerase (also called Phosphohexose Isomerase)
  3. Step 3: Phosphofructokinase-1 (PFK-1)
  4. Step 4: Aldolase
  5. Step 5: Triose Phosphate Isomerase
  6. Step 6: Glyceraldehyde-3-phosphate Dehydrogenase
  7. Step 7: Phosphoglycerate Kinase
  8. Step 8: Phosphoglycerate Mutase
  9. Step 9: Enolase
  10. Step 10: Pyruvate Kinase