Lecture notes - Cell And Molecular Biology (Respiration part 2) - using Becker's World of the Cell, Global Edition

Glycolysis:
Glycolysis = sugar splitting – 6 C12 = broken down into 2 X 312 – (2 X Pyruvate) – Occurs in cytosol
(cytoplasmic matrix)

Phosphorylation addition makes a molecule more chemically reactive

2 stages in Glycolysis:

Energy investment phase:

- 1 X ATP used to convert Glucose into Glucose 6-phosphate (Hexokinase enzyme catalysation)
- Glucose Phosphate is converted into Fructose 6-phosphate (Phosphoglucoisomerase enzyme
catalysation)
- 1 X ATP used to convert Fructose 6-phosphate into Fructose 1,6-bisphosphate
(Phosphofructokinase enzyme catalysation)
- Aldolase enzyme converts this into 2 x 3 C12 molecule

Energy payoff phase:

(Very complex process – use textbook diagrams) But in summary:

- In a series of reactions – G3P = converted into Pyruvate
- H+ combines with NAD forming NADH
- ADP + Pi combines to form ATP
- Several enzymes used in this process




During Glycolysis:

- No C12 released as CO2
- Glycolysis occurs regardless of the presence of O2

Citric acid/Krebs cycle:

Pyruvate enters mitochondrion via active transport

Converted into acetyl CoA via 3 catalysed reactions:

- Carboxyl group on Pyruvate = fully oxidised – released as CO2 molecule
- Remaining 2C12 molecule = oxidised, E- transferred to NAD+ forming NADH (stores energy)