Brent Cornell

    
Aerobic respiration involves the breakdown of glucose in the presence of oxygen to produce water and carbon dioxide

• It requires the involvement of mitochondria and generates a large yield of ATP (typically 36 ATP per glucose consumed)
• Aerobic respiration may include the following processes:  glycolysis, link reaction, krebs cycle, electron transport chain

Aerobic Respiration Equation

Types of Aerobic Reactions

Aerobic respiration involves three main types of reactions – decarboxylation, oxidation and phosphorylation

• The following table organises these reactions according to the different stages of aerobic respiration
  

Decarboxylation:

• Carbon atoms are removed from the organic molecule (glucose) to form carbon dioxide
• Aerobic respiration involves the complete combustion of glucose (6C) – so six CO₂ molecules are produced

Oxidation:

• Electrons and hydrogen ions are removed from glucose and taken up by hydrogen carriers (NADH and FADH₂)
• The hydrogen carriers are in turn oxidised at the electron transport chain (where the energy is used to make ATP)
• The electrons and hydrogen ions are then taken up by oxygen (reduction) to form water molecules
• Twelve hydrogen carriers are produced and so six oxygen molecules are required (12 × O = 6 × O₂)

Phosphorylation:

• Energy released from the breakdown of glucose is used to phosphorylate ADP to make ATP
• A net total of four ATP molecules are produced directly via substrate level phosphorylation
• The remaining ATP is produced indirectly via the electron transport chain (oxidative phosphorylation)

Summary of the Stages of Aerobic Respiration

ATP Production

Aerobic respiration typically produces a net total of 36 ATP per molecule of glucose consumed

• A net total of 2 ATP are produced in glycolysis via substrate level phosphorylation (four are produced, but two are consumed)
• A further 2 ATP are similarly produced in the Krebs cycle (one ATP per cycle – two cycles occur per glucose molecule)
• Lastly, 32 ATP are produced in the electron transport chain using energy from hydrogen carriers (oxidative phosphorylation)

Hydrogen carriers produce different amounts of ATP depending on where they donate electrons to the transport chain

• NADH molecules located in the matrix donate electrons to the start of the chain and produce 3 ATP per hydrogen carrier
• Cytosolic NADH (from glycolysis) donate electrons later in the chain and only produce 2 ATP per hydrogen carrier
• FADH₂ also donates electrons later in the chain and so only produce 2 ATP per hydrogen carrier

Oxidative phosphorylation:  (8 × matrix NADH) + (2 × cytosolic NADH) + (2 × FADH₂)  =  (8 × 3) + (2 × 2) + (2 × 2)  =  32 ATP

Summary of ATP Production

Overview of Aerobic Respiration