Anaerobic Respiration and Fermentation Notes

Anaerobic Respiration/Fermentation

• Occurs without oxygen.
• Glucose is broken down without oxygen.
• Less ATP is produced compared to aerobic respiration.

Glycolysis

• Glucose (6C) is converted to 2 Pyruvic acid (PGA) (3C compound).
• Net gain of 2 ATP.
• 2NAD+ is converted to 2NADH
• In the absence of oxygen, pyruvic acid undergoes fermentation.

Lactic Acid Fermentation

• Occurs in some bacteria and mammal muscles.
• Pyruvic acid is converted to lactic acid.
• No CO2 is produced.
• Lactic acid buildup can cause muscle stiffness.
• Lactic acid can be broken down later via the Krebs cycle if oxygen becomes available.

Alcoholic Fermentation

• Occurs in yeast and some plants.
• Pyruvic acid is converted to ethanol (alcohol) and CO2.
• Important in beer, wine, and bread production.

Yeast and Bread Making

• Bread yeast (Saccharomyces cerevisiae) reproduces by budding.
• Releases CO2, causing bread to rise.

Comparison of Aerobic and Anaerobic Respiration

• Aerobic Respiration:
  • Raw materials: Glucose and Oxygen
  • Products: CO2 and Water
  • Energy: 38 ATP molecules (per glucose)
• Anaerobic Respiration:
  • Raw materials: Glucose
  • Products:
    • Plants: Alcohol and CO2
    • Animals: Lactic acid
  • Energy: 2 ATP molecules (per glucose)