• Glycolysis is the first stage of respiration
• It does not require oxygen to take place and is therefore the first step for both aerobic and anaerobic respiration
• Glucose is only?partially?oxidised?during glycolysis
• It takes place in the cytoplasm of the cell and involves:
  • Trapping glucose?in the cell by?phosphorylating?the molecule
  • Oxidising?triose phosphate (by losing hydrogen)
• It results in the production of
  • 2 Pyruvate?(3C) molecules which moves into the matrix of mitochondria to be used during the link reaction
  • Net gain?2 ATP
  • 2 reduced?NAD, which will be used during a later stage called oxidative phosphorylation
• Under?anaerobic?conditions, glycolysis produces?lactic acid or lactate?instead of pyruvate

Steps of glycolysis

• Phosphorylation?of glucose (a hexose sugar)
  • Two molecules of ATP are required to provide the?two phosphates?needed for the phosphorylation of glucose
  • This produces
    • Two molecules of triose phosphate
    • Two molecules of ADP
• Oxidation?of triose phosphate
  • After triose phosphate?loses hydrogen, it forms?two molecules of pyruvate
  • The?hydrogen ions are collected by NAD?which reduces the coenzyme
  • This forms?two reduced NAD or NADH
  • Even though a total of four ATP molecules were produced during glycolysis, two of them were used to phosphorylate glucose
  • There was therefore a?net gain of two ATP molecules

The process of glycolysis