Aerobic and Anaerobic Respiration

Introduction

• All organisms respire to release energy for living processes.
• Respiration can be aerobic (using oxygen) or anaerobic (without oxygen).

Aerobic Respiration

• Definition: Respiration using oxygen to break down food molecules.
• Main Substrate: Glucose.
• Location: Begins in cytoplasm; most energy released in mitochondria.
• Equation:
  • Word: Glucose + Oxygen → Carbon Dioxide + Water + Energy
  • Chemical: C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy
• Characteristics:
  • Oxygen is required.
  • Complete oxidation of glucose.
  • Products: Carbon dioxide and water, which do not contain stored energy.
  • Releases a large amount of energy.

Anaerobic Respiration

• Definition: Respiration without oxygen.
• Human Muscle Respiration: Converts glucose to lactic acid + energy.
• Equation: Glucose → Lactic Acid + Energy
• Yeast and Some Plants:
  • Converts glucose to ethanol + carbon dioxide + energy.
  • Equation: Glucose → Ethanol + Carbon Dioxide + Energy
• Characteristics:
  • No oxygen required.
  • Incomplete oxidation of glucose.
  • Products: Lactic acid in muscles; ethanol and carbon dioxide in yeast/plants.
  • Releases a small amount of energy quickly.
  • Occurs only in the cytoplasm.

Comparison of Aerobic and Anaerobic Respiration

• Presence of Oxygen:
  • Aerobic: Present
  • Anaerobic: Absent or limited
• Oxidation of Glucose:
  • Aerobic: Complete
  • Anaerobic: Incomplete
• Products:
  • Aerobic: Carbon dioxide and water
  • Anaerobic: Lactic acid (muscles), ethanol and carbon dioxide (yeast/plants)
• Energy Released:
  • Aerobic: Large amount
  • Anaerobic: Small amount, quickly

Further Learning

• Cellular Respiration
• Anaerobic Respiration
• Response to Exercise
• Oxygen Debt and the Liver
• Metabolism

Related Topics

• Photosynthesis
• Sample Exam Questions - Bioenergetics