The last five reactions of glycolysis leads to production of two pyruvate molecules. The last five reactions are called the energy harvesting or energy payoff phase.
Reaction 6: Glyceraldehyde-P Dehydrogenase Reaction
G3P is converted to 1, 3 bisphosphoglycerate
This is the first reaction in glycolysis to generate a NADH molecule. NADH is an electron carrier that is used in the mitochondrion by the ETC to generate ATP.
Reaction 7: Phosphoglycerate kinase converts 1,3 BPG to 3-phosphoglycerate. It is the first step of glycolysis to generate ATP via substrate level phosphorylation. A phosphate group is removed from 1,3 BPG and transferred to ADP to form ATP (substrate-level phosphorylation).
Reaction 8: Phosphoglycerate mutase converts 3-phosphoglycerate to 2-phosphoglycerate.
What is the purpose of this reaction?
This rearrangement of the phosphate from the C-3 to C-2 position allows productio of phosphoenolpyruvate in the next reaction.
Reaction 9: Enolase converts 2-PG to PEP
Reaction 10: Pyruvate kinase converts PEP to pyruvate and also generates ATP via substrate level phosphorylation.
Sunday, June 12, 2011
Summary of the First Five Reactions in Glycolysis
The first five reactions of glycolysis are referred to as the energy investment phase or energy input phase. These reactions initially use ATP. Reaction 1 uses an ATP molecule to convert glucose to glucose 6-phosphate. This input of energy is similar to priming a pump. Some energy must be used to initiate or start the reactions of the glycolytic pathway.Reaction 3 uses a second ATP molecule to convert F6P to F 1,6-BP.
The first phase converts glucose (a 6 carbon molecule) to two glyceralde 3-phosphate molecules (3 carbon molecules).
The first phase converts glucose (a 6 carbon molecule) to two glyceralde 3-phosphate molecules (3 carbon molecules).
Steps 4 & 5 of Glycolysis
In step 4 fructose 1,6-bisphosphate is cleaved by fructose bisphosphate aldolase to form dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (G3P). This reaction is unfavorable written at standard state. Cellularly, the change in free energy is close to zero.
In step 5 DHAP is converted to G3P by triose phosphate isomerase.
Why is DHAP converted to G3P?
The purpose of this reaction is to allow both products of the aldolase reaction to continue in glycolysis.
In step 5 DHAP is converted to G3P by triose phosphate isomerase.
Why is DHAP converted to G3P?
The purpose of this reaction is to allow both products of the aldolase reaction to continue in glycolysis.
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