Fermentation

Stages of Fermentation

1. Glycolysis

• Process: Glucose is broken down into pyruvate.

• Inputs:

  • 1 glucose molecule (C6H12O6)

  • 2 NAD+ molecules

  • 2 ADP molecules

• Outputs:

  • 2 pyruvate molecules

  • 2 NADH molecules

  • 2 ATP (net gain)

2. Waste Product Formation

• Two types of fermentation:

A. Alcoholic Fermentation

• Chemical Equation: [ C6H{12}O6 ightarrow 2 CH3CH2OH + 2 CO2 + 2 ext{Energy} (2 ext{ATP}) ]

• Process of Alcoholic Fermentation:

  • Conversion of pyruvate to ethanol.

  • Breakdown:

  • 2 pyruvate converted to 2 aldehyde, releasing 2 CO₂.

  • 2 aldehyde are then converted to 2 ethanol, oxidizing 2 NADH into 2 NAD+.

• Waste Products: CO₂ and ethanol diffuse from the cells.

B. Lactic Acid Fermentation

• Chemical Equation: [ C6H{12}O6 ightarrow 2 CH3CH(OH)COOH + 2 ext{Energy} (2 ext{ATP}) ]

• Process of Lactic Acid Fermentation:

  • Conversion of pyruvate to lactate (lactic acid).

  • Breakdown:

  • 2 pyruvate converted to 2 lactate, oxidizing 2 NADH into 2 NAD+.

• Location: Occurs in muscle cells, which are facultative anaerobes.

• Oxygen Availability:

  • Muscle cells utilize O₂ when available.

  • Can switch to lactic acid fermentation in times of oxygen debt.

Summary of Alcoholic and Lactic Acid Fermentation

• Alcoholic Fermentation: Produces ethanol and carbon dioxide from glucose under anaerobic conditions, yielding a net gain of 2 ATP.

• Lactic Acid Fermentation: Converts glucose into lactic acid under anaerobic conditions, also yielding a net gain of 2 ATP.

• Commonalities: Both types begin with glycolysis where glucose is partially oxidized, resulting in the production of energy carriers and ATP.