bio 107

Glycolysis Overview

• Glycolysis is a key metabolic pathway that converts glucose into pyruvate, resulting in the production of ATP.

Initial Investment Phase

• Conversion of Glucose to Fructose

  • Isomerization of Glucose 6-Phosphate (G6P) to Fructose 6-Phosphate (F6P).

  • Enzyme: Isomerase.

  • This reaction sets up further steps in glycolysis by forming an isomer.

• ATP Investment:

  • The first ATP is invested in the conversion of F6P to Fructose 1,6-Bisphosphate (F1,6BP).

  • Enzyme: Phosphofructokinase

    • This enzyme is crucial for regulating glycolysis and is a one-way reaction.

    • Cannot revert from F1,6BP back to F6P.

Cleavage Phase

• Cleavage of Fructose 1,6-Bisphosphate:

  • The molecule is split into two three-carbon molecules.

  • Products:

  • Glyceraldehyde 3-Phosphate (G3P)

  • Dihydroxyacetone Phosphate (DHAP)

  • Enzyme: Aldolase

  • Aldolase can interconvert G3P and DHAP.

  • For the sake of this discussion, assume that DHAP is converted to G3P via isomerization.

Energy Extraction Phase

• Oxidation of G3P:

  • Electrons are transferred from G3P to NAD+, reducing it to NADH, which is crucial for energy production.

  • Inorganic phosphate (Pi) is added to G3P, forming 1,3-Bisphosphoglycerate (1,3-BPG).

  • Enzyme: Glyceraldehyde 3-Phosphate Dehydrogenase.

• Formation of ATP:

  • Dephosphorylation of 1,3-BPG:

  • One phosphate group is transferred to ADP to form ATP.

  • Product: 3-Phosphoglycerate (3-PGA)
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