AEROBIC RESPIRATION

Learning Objectives for this Section

Aerobic respiration (def) is the aerobic catabolism of nutrients to carbon dioxide, water, and energy, and involves an electron transport system (def) in which molecular oxygen is the final electron acceptor. Most eukaryotes and prokaryotes use aerobic respiration to obtain energy from glucose. The overall reaction is:

C6H12O6 + 6O2 yields 6CO2 + 6H2O + energy (as ATP)

Note that glucose (C6H12O6 ) is oxidized to produce carbon dioxide (CO2) and oxygen (O2) is reduced to produce water (H2O).

This type of ATP production is seen in aerobes and facultative anaerobes. Aerobes are organisms that require molecular oxygen because they produce ATP only by aerobic respiration. Facultative anaerobes, on the other hand are capable of aerobic respiration but can switch to fermentation, an anaerobic ATP-producing process, if oxygen is unavailable.

Aerobic respiration involves four stages: glycolysis, a transition reaction that forms acetyl coenzyme A, the citric acid (Krebs) cycle, and an electron transport chain and chemiosmosis. We will now look at each of these stages.

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Updated: June 26, 2001