Final Glycolysis

What is the energetic yield of Glycolysis per glucose molecule?

2 ATP (4 ATP generated, 2 consumed in the preparatory phase) and 2 NADH

What is the location and overall function of Glycolysis?

Glycolysis occurs in the cytoplasm (cytosol) and is the first part of glucose oxidation, converting one molecule of glucose into two molecules of pyruvate

Role of phosphorylation

Traps glucose inside the cell as it makes it so that it Cannot be transported back out by GLUT carriers.

What are the two Glycolysis steps that perform substrate-level phosphorylation (directly generating ATP)?

Reaction 7 (Phosphoglycerate Kinase) and Reaction 10 (Pyruvate Kinase)

Irreversible steps of Glycolysis

Reaction 1 (Hexokinase), Reaction 3 (PFK-1), and Reaction 10 (Pyruvate Kinase)

Where does pyruvate go when oxygen is plentiful?

Pyruvate is converted to Acetyl-CoA by the pyruvate dehydrogenase complex (PDC) inside the mitochondria, and the Acetyl-CoA then enters the TCA cycle

What is the result of fermentation in human cells?

Pyruvate is reduced to Lactate by lactate dehydrogenase, which regenerates NAD+ to sustain glycolysis and minimal ATP production when oxygen is low

R1 of Glycolysis

Enzyme: Hexokinase 
Line: Glucose → Glucose 6-phosphate (G6P)
Delta G = Highly Negative
Key concepts: 1 ATP consumed

R2 of Glycolysis

Enzyme: Phosphohexose Isomerase
Line: G6P ⇌ Fructose 6-phosphate (F6P)

R3 of Glycolysis

Enzyme: Phosphofructokinase-1 (PFK-1)
Line: F6P → Fructose 1,6-bisphosphate (F1,6BP)
Delta G = Highly Negative
Key concepts: 1 ATP consumed (commited step and highly regulated)

R4 of Glycolysis

Enzyme: Aldolase
Line: F1,6BP ⇌ Dihydroxyacetone phosphate (DHAP) + Glyceraldehyde 3-phosphate (G3P)
Delta G = Highly positive

R5 of Glycolysis

Enzyme: Triose Phosphate Isomerase
Line: DHAP ⇌ G3P
Key concepts: Ensures the DHAP from R4 is converted to G3P so glycolysis can continue

R6 of Glycolysis

Enzyme: Glyceraldehyde 3-phosphate Dehydrogenase
Line: G3P + Pi​ + NAD+→ 1,3-Bisphosphoglycerate (BPG) +NADH+H+
Key concepts: PRODUCES 1 NADH (2 PER GLUCOSE) AND USES A Pi

R7 of Glycolysis

Enzyme: Phosphoglycerate Kinase
Line: BPG + ADP → 3-Phosphoglycerate + ATP
Delta G = Highly Negative
Key concepts: 1 ATP consumed

R8 of Glycolysis

Enzyme: Phosphoglycerate Mutase
Line: 3-Phosphoglycerate ⇌ 2-Phosphoglycerate

R9 of Glycolysis

Enzyme: Enolase
Line: 2-Phosphoglycerate → Phosphoenolpyruvate (PEP) +H2​O

Key concepts: Generates a high energy compound PEP

R10 of Glycolysis

Enzyme: Pyruvate Kinase
Line: PEP + ADP → Pyruvate + ATP
Delta G = Highly Negative
Key concepts: 1 ATP consumed, tautermizaion of product drives reaction foward.