II. BACTERIAL GROWTH AND MICROBIAL METABOLISM

D. Cellular Respiration

1. Aerobic Respiration

Fundamental statements for this learning object:

1. Aerobic respiration is the aerobic catabolism of nutrients to carbon dioxide, water, and energy, and involves an electron transport system in which molecular oxygen is the final electron acceptor.
2. The overall reaction is: C₆H₁₂O₆ + 6O₂ yields 6CO₂ + 6H₂O + energy (as ATP). Glucose (C₆H₁₂O₆ ) is oxidized to produce carbon dioxide (CO₂) and oxygen (O₂) is reduced to produce water (H₂O).
3. This type of ATP production is seen in aerobes and facultative anaerobes.
4. 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.

Learning Objectives for this Section

Cellular respiration (def) is the process cells use to convert the energy in the chemical bonds of nutrients to ATP energy. Depending on the organism, cellular respiration can be aerobic, anaerobic, or both. Aerobic (def) respiration is an exergonic pathway that requires molecular oxygen (O₂). Anaerobic (def) exergonic pathways do not require oxygen and include anaerobic respiration and fermentation. We will now look at these three pathways.

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).