Anaerobic Respiration
• In anaerobic conditions (no oxygen), cells can obtain
energy through the process of anaerobic respiration.
• Fermentation is an anaerobic process that allows
glycolysis (also anaerobic) to continue making ATP in
the absence of oxygen.
• Not as efficient as aerobic respiration (less ATP)
• Occurs in cytoplasm
Anaerobic Respiration
• Two types of fermentation:
– Lactic acid Fermentation
– Alcoholic Fermentation
Lactic acid Fermentation
• Occurs in muscle cells during rapid & vigorous exercise
when a lot of energy is required & oxygen is scarce
(oxygen debt).
– Also used by bacteria in the production of food products like
yogurt
• The pyruvic acid formed during glycolysis is broken
down to lactic acid, and in the process energy is
released, which can be used in glycolysis to make ATP.
– Glucose  pyruvic acid  lactic acid + ATP
Aerobic vs Anaerobic Respiration
Alcohol Fermentation
• Occurs in many yeasts
• Pyruvic acid (formed during glycolysis) is
broken down to produce CO2 and ethanol
Glucose  pyruvic acid  alcohol + CO2 + ATP
– The bubbles formed by the CO2 make
bread rise
– The alcohol released turns grape juice into wine
Photosynthesis vs. Cellular Respiration
Photosynthesis
Stores Energy as glucose
Cellular Respiration
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Releases Energy in glucose
Occurs in Living Cells
Uses an Electron Transport
Chain
Occurs in Plant Cells
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Occurs in Animal Cells
Releases Oxygen

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Releases Carbon Dioxide
Creates Energy

Neither!