Glycolysis

Glycolysis

  • first stage of aerobic respiration

  • occurs in the cytoplasm of cells

  • breaks glucose (6C) into 2 pyruvate (3C) molecules

    • enzyme controlled reactions

  • does not require oxygen so is anaerobic process

  • produces:

    • pyruvate

    • small amounts of ATP

    • reduced NAD

stages of glycolysis

Phosphorylation of glucose

  • 2x ATP molecules donate phosphate groups to glucose

  • forms hexose bisphosphate

Lysis

  • hexose bisphosphate is split into two molecules of triose phosphate (TP)

Phosphorylation of TP

  • second phosphate group is added to each TP molecule

  • converts them into 2x triose bisphosphate

Dehydrogenation

  • a hydrogen is removed from each triose bisphosphate molecule

    • they are oxidised

  • used to form:

    • 2x reduced NAD

    • 2x pyruvate

    • 4x ATP

      • substrate level phosphorylation

        • formation of ATP without involvement of an electron transport chain

        • after glycolysis - if oxygen is available - pyruvate moves through mitochondrial membranes by active transport

Reactants and products of glycolysis

  • reactants

    • 1x glucose

    • 2x ATP

  • products

    • 4x ATP

    • 2x reduced NAD

    • 2x pyruvate

  • net energy gain is 2x ATP and 2x reduced NAD per glucose molecule processed