There is chemical logic to the steps in a pathway. Each reaction serves some che
ID: 61092 • Letter: T
Question
There is chemical logic to the steps in a pathway. Each reaction serves some chemical purpose in helping the pathway reach its goal. Put the important chemical transformation in the order they occur during the second phase of glycolysis.
A mixed anhydride bond in a "high-energy" intermediate is used to carry out substrate-level phosphorylation forming ATP.
Elimination of water results in the formation of a "high-energy" compound.
Carbon is oxidized and NAD+ is reduced. Energy from this oxidation is used to add inorganic phosphate to the substrate forming a "high-energy" compound.
The position of the phosphate group is changed to set up the next reaction in the pathway.
Transfer of a phosphoryl group to ADP during substrate-level phosphorylation allows the product to tautomerize releasing energy to drive the reaction.
Explanation / Answer
1. Transfer of a phosphoryl group to ADP during substrate-level phosphorylation allows the product to tautomerize releasing energy to drive the reaction.
2. Carbon is oxidized and NAD+ is reduced. Energy from this oxidation is used to add inorganic phosphate to the substrate forming a "high-energy" compound.
3. The position of the phosphate group is changed to set up the next reaction in the pathway.
4. Elimination of water results in the formation of a "high-energy" compound.
5. A mixed anhydride bond in a "high-energy" intermediate is used to carry out substrate-level phosphorylation forming ATP.
The following are the series of steps in glycolysis,
The flow of electrons and the flow of phosphorus atoms: In the first step, the glucose is phosphorylated by the enzyme hexokinase. One phosphate molecule from ATP is transferred into glucose resulting in the prodution og glucose-6-phosphate and ADP.
Glucose+ hexokinase + ATP -----------> Glucose-6-phosphate + ADP
2) Glucose-6-phosphate now isomerises to fructose-6-phosphate by th eenzyme phosphoglucoisomerase.
3) Fructose-6-phosphate again undergoes phosphorylation process in the presence of phosphofructokinase by gaining a phosphate group from the ATP, resulting in the production of fructose-1,6-bisphosphate.
Fructose-6-phosphate + ATP + phosphofructokinase --------------------> fructose-1,6-bisphosphate + ADP
4) Fructose-1,6-bisphosphate now undergoes a destabilization reaction in the presence of aldolase enzyme giving rise to the production of two isomers namely dihydroxyacetone phosphate and glyceraldehyde phosphate.
5). Now, the glyceraldehyde -3-phosphate undergoes dehydrogenation in the presence of triose phosphate dehydrogenase and adds an inorganic phosphate resulting in the formation of 1,3-bisphosphoglycerate. During this process, two NAD+ molecules are converted into NADH and two hydrogen ions are formed. glyseraldehyde-3- phosphate + triose phosphate dehydrogenase + 2 NAD+ + 2Pi + 2H- -------------> Two molecules of 1,3- bisphosphoglycerate + 2 NADH + 2H+
6) One phosphate from the 1,3- bisphosphoglycerate is now transferred to an ADP molecule forming an ATP molecule thus, forming 1 ATP molecules (from each 1,3- bisphosphoglycerate) and two molecules of 3- phosphoglyserate.
7) 3- phosphoglyserate is converted into 2-phosphoglycerate in the presence of phosphoglycerokinase.
8) One molecule of water is removed from each phosphoglcerate to form 2 molecules of phosphoenolpyruvic acid in the presence of enolase enzyme.
9) An inorganic moleule is transferred from the phosphoenolpyruvic acid to ADP resulting in the formation of pyruvic acid and ATP, this reaction occurs in the presence of pyruvate ki.nase.
2 Phosphoenolpyruvic acid + 2 ADP + pyruvate kinase -----------------> 2 ATP + 2 Pyruvic acid
Thus, the net yield in glycolysis is two molecules of pyruvic acid and two ATP molecules.
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