Steps in Glycolysis and CAC

Hexokinase

Step 1:

Reaction: Glucose → Glucose-6-phosphate

Type: Phosphorylation, ATP investment

Note: Irreversible, regulated step

Phosphoglucose Isomerase

Step 2:

Reaction: Glucose-6-phosphate ⇌ Fructose-6-phosphate

Type: Isomerization

Phosphofructokinase-1 (PFK-1)

Step 3:

Reaction: Fructose-6-phosphate → Fructose-1,6-bisphosphate

Type: Phosphorylation, ATP investment

Note: Irreversible, rate-limiting step, regulated

Aldolase

Step 4:

Reaction: Fructose-1,6-bisphosphate ⇌ Dihydroxyacetone phosphate (DHAP) + Glyceraldehyde-3-phosphate (GAP)

Type: Lysis (cleavage)

Triose Phosphate Isomerase

Step 5:

Reaction: DHAP ⇌ GAP

Type: Isomerization

Note: Ensures two GAP molecules enter payoff phase

Glyceraldehyde-3-phosphate Dehydrogenase (GAPDH)

Step 6:

Reaction: GAP + NAD+ + Pi ⇌ 1,3-Bisphosphoglycerate + NADH

Type: Oxidation + Phosphorylation

Note: Produces NADH

Phosphoglycerate Kinase

Step 7:

Reaction: 1,3-BPG + ADP ⇌ 3-Phosphoglycerate + ATP

Type: Substrate-level phosphorylation

Note: First ATP payoff step

Phosphoglycerate Mutase

Step 8:

Reaction: 3-Phosphoglycerate ⇌ 2-Phosphoglycerate

Type: Isomerization

Enolase

Step 9:

Reaction: 2-Phosphoglycerate ⇌ Phosphoenolpyruvate (PEP) + H₂O

Type: Dehydration

Note: Forms high-energy intermediate

Pyruvate Kinase

Step 10:

Reaction: PEP + ADP → Pyruvate + ATP

Type: Substrate-level phosphorylation

Note: Irreversible, regulated step

Step 11: