The Four Stages in Aerobic Respiration (CIE A Level Biology)

Where does aerobic respiration occur?

• Glucose is the main respiratory substrate used by cells
• Aerobic respiration is the process of breaking down a respiratory substrate in order to produce ATP using oxygen
• The process of aerobic respiration using glucose can be split into four stages
• Each stage occurs at a particular location in a eukaryotic cell:
  • Glycolysis takes place in the cell cytoplasm
  • The Link reaction takes place in the matrix of the mitochondria
  • The Krebs cycle takes place in the matrix of the mitochondria
  • Oxidative phosphorylation occurs at the inner membrane of the mitochondria

Four Stages of Respiration Table

Stage	Description	Location
1. Glycolysis	Phosphorylation and splitting of glucose	Cell cytoplasm
2. Link reaction	Decarboxylation and dehydrogenation of pyruvate	Matrix of mitochondria
3. Krebs cycle	Cyclical pathway with enzyme-controlled reactions	Matrix of mitochondria
4. Oxidative phosphorylation	Production of ATP through oxidation of hydrogen atoms	Inner membrane of mitochondria