12 Glycolysis

1) Phosphorylation of glucose to glucose phosphate

• Glucose is made more reactive
• Addition of two phosphate molecules
• Requires 2 ATP molecules (become ADP)
• Lowers the activation energy for enzyme-controlled reactions

2) Splitting of phosphorylated glucose

• Each glucose is split into two 3-carbon molecules (triose phosphate)

3) Oxidation of triose phosphate

• Hydrogen is removed from each triose phosphate
• Transferred to NAD turning it into reduced NAD

4) The production of ATP

• Enzyme-controlled reactions convert each triose phosphate into pyruvate
• Per reaction, 2 ATP are produced, 4 per glucose

• In total per glucose:
  • two molecules of ATP - 4 are produced but two are needed for the phosphorylation of glucose
  • two molecules of reduced NAD - have the potential to provide more energy to produce ATP - oxidative phosphorylation
  • two molecules of pyruvate
• Universal for every living organism
• Indirect evidence for evolution
• Happens in the cytoplasm - doesn't require membrane-bound organelles
• Doesn't require oxygen
• Can be converted into ethanol or lactate - anaerobic respiration
• This is necessary to re-oxidise the NAD for more glycolysis
• Anaerobic respiration only yields a small amount of energy compared to aerobic respiration