Question

Reactions that occur in glycolysis can all be described in terms of the chemical changes that occur within each. Place the descriptions of these chemical reactions in the order that they occur in stage II of glycolysis (from beginning to end).

Answer 1

Payoff Stage of Glycolysis:-

Step 6:- The two molecules of glyceraldehyde-3-phosphate are oxidized. Enzyme glyceraldehyde-3-phosphate dehydrogenase catalyzes the conversion of glyceraldehyde-3-phosphate into 1,3-bisphosphoglycerate (1,3-BPG). The reaction occurs in two steps: first the oxidation of the aldehyde to a carboxylic acid by NAD⁺ and second the joining of the carboxylic acid and orthophosphate to from the acyl-phosphate product. Iodoacetate is a potent inhibitor of glyceraldehyde-3-phosphate dehydrogenase because it forms a covalent derivative of the essential -SH group of the enzyme active site, rendering it inactive.

Step 7:- In this step high-energy phosphate group is transferred from 1,3-bisphosphoglycerate to ADP. The formation of ATP is referred to as substrate-level phosphorylation becasue the phosphate donor, 1,3-bisphosphoglycerate, is a substrate with high phosphoryl-transfer potential.This step is catalyzed by enzyme phosphoglycerate kinase.

Step 8:- The remaining phosphate ester linkage in 3-phosphoglycerate, which has a relatively low free energy of hydrolysis, is moved from carbon 3 to carbon 2 to form 2-phosphoglycerate.

Step 9:- The removal of water from 2-phosphoglycerate creates a high-energy enol phosphate linkage. The enzyme catalyzing this step, enolase, is inhibited by fluoride.

Step 10:- The transfer of high-energy phosphate group that was generated in step 9 to ADP forms ATP. This last step in glycolysis is the irreversible transfer of the phosphoryl group from phosphenolpyruvate to ADP is catalyzed by pyruvate kinase. Pyruvate kinase requires enter K⁺ or Mg²⁺.