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What is glycolysis? How many steps are in glycolysis and what are they? What are the three key regulatory steps? Which step is irreversible and why? What are the enzymes that participate in glycolysis?


What is glycolysis? How many steps are in glycolysis and what are they? What are the three key regulatory steps? Which step is irreversible and why? What are the enzymes that participate in glycolysis? 

Step 1

Glycolysis is the process of reaction by which one molecule of glucose is converted to two molecules of pyruvate in which a sequence of 10 enzyme-catalyzed reactions occurs. In this process the net production of 2 ATP and the reduction of 2 NAD+ to 2 NADH occur.

Step 2

In glycolysis reaction 10steps are involved to convert glucose to pyruvate and those are as follows:

  • In Reaction 1 of glycolysis, a phosphoryl group is transferred from ATP to glucose to form glucose-6-phosphate (G6P) in a catalytic reaction continues by hexokinase. In this reaction kinase is act as an enzyme that transfers the phosphoryl groups between ATP and a metabolite. Metabolite serves the phosphoryl group acceptor.
  • Reaction 2 of glycolysis explains the conversion of glucose-6-phosphate (G6P) and fructose-6-phosphate (F6P) in presence of phosphor-glucose isomerase (PGI). This reaction represents the isomerization of an aldose to a ketone.
  • In Reaction 3 of glycolysis, phosphofructokinase (PFK) phosphorylates fructose-6-phosphate (F6P) to form fructose-1,6-biphosphate (FBP).
  • Reaction 4 of glycolysis pathway, aldolase catalyzes the cleavage of fructose-1, 6-biphosphate to form the two trioses glyceraldehyde-3-phosphate (GAP) and dihydroxyacetone phosphate. This represents the carbon-carbon cleavage occurs in retro aldol condensation. The cleavage is occurs in between C3 and C4 of fructose-1, 6-biphosphate.
  • Reaction 5 represents the products of the of the aldol cleavage reaction, in which glyceraldehyde-3-phosphate converted to dihydroxyacetone phosphate. In this reaction interconversion occurs by an isomerization reaction with an enediol intermediate. Triose phosphate isomerase catalyzes this process in this reaction of glycolysis.
  • Reaction 6 of glycolysis represents the oxidation and phosphorylation of glyceraldehyde-3-phosphate (GAP) in presence of NAD+ and Pi as catalyzed by glyceraldehyde-3-phosphate dehydrogenase to form 1, 3-Bisphosphoglycerate.
  • Reaction 7 of glycolysis pathway yields ATP with 3-phosphoglycerate (3GP) in a reaction that is catalyzed by enzyme phosphoglycerate kinase (PGK). In this reaction reverse phosphorylation occurs in presence of kinase enzyme. From 1, 3-Bisphosphoglycerate one phosphate group is transferred to 3-phosphoglycerate (3GP) and ATP.
  • Reaction 8 of glycolysis represents the conversion of 3-phosphoglycerate (3PG) to 2-phosphoglycerate in presence of phosphoglycerate mutase. This reaction also represents the isomerization reaction.
  • Reaction 9 of glycolysis explains the dehydration reaction in which 2-phosphoglycerate is dehydrated to phosphoenolpyruvate (PEP) in a reaction that is catalyzed by enolase.
  • In the final reaction, Reaction 10 of glycolysis pyruvate kinase enhances the phosphoenolpyruvate in presence of ADP form pyruvate and ATP. The pyruvate kinase reaction is highly exergonic that gives more energy to drive ATP synthesis, a substrate-level phosphorylation reaction.
Step 3

The three regulatory steps of glycolysis are step 1, step 3, and step 10 because these reactions in this step are irreversible and phosphorylation reaction occur...

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