Glycolysis (AQA A Level Biology)

• Glycolysis is the first stage of respiration
• It takes place in the cytoplasm of the cell and involves:
  • Trapping glucose in the cell by phosphorylating the molecule
  • Splitting the glucose molecule in two

• It results in the production of
  • 2 Pyruvate (3C) molecules
  • Net gain 2 ATP
  • 2 reduced NAD

Steps of glycolysis

• Phosphorylation: glucose (6C) is phosphorylated by 2 ATP to form fructose bisphosphate (6C)

Glucose + 2ATP → Fructose bisphosphate

• Lysis: fructose bisphosphate (6C) splits into two molecules of triose phosphate (3C)

Fructose bisphosphate → 2 Triose phosphate

• Oxidation: hydrogen is removed from each molecule of triose phosphate and transferred to coenzyme NAD to form 2 reduced NAD

4H + 2NAD → 2NADH + 2H⁺

• Dephosphorylation: phosphates are transferred from the intermediate substrate molecules to form 4 ATP through substrate-linked phosphorylation

4P_i + 4ADP → 4ATP

• Pyruvate is produced: the end product of glycolysis which can be used in the next stage of respiration

2 Triose phosphate → 2 Pyruvate

The process of glycolysis