Fermentation

Fermentation Overview

  • Fermentation is a metabolic process that allows cells to generate energy from food molecules in the absence of oxygen.

Meet Raquel

  • Raquel is a 34-year-old nurse training for the Boston Marathon.

  • She consumed a carbohydrate-rich meal before the race.

  • Initial performance was strong at mile 5; however, by mile 13, fatigue set in.

  • Glucose gummies helped her regain energy.

  • At mile 20, she faced intense physical challenges, referred to as 'hitting the wall.'

Cellular Respiration Basics

  • Definition: A process that releases chemical energy from food, fundamentally requiring oxygen (aerobic process).

  • Equation:

    • Oxygen + Glucose → Carbon Dioxide + Water + ATP

Fermentation Process

  • Anaerobic Process: Fermentation occurs when oxygen is not present, enabling energy extraction from food.

  • Primarily happens in the cytoplasm of cells.

  • During exercise, muscle cells may not get enough oxygen, leading to lactate production through fermentation in addition to ATP production from glycolysis.

Types of Fermentation

1. Lactic Acid Fermentation

  • Who: Animals and some bacteria.

  • Location: Cytoplasm.

  • Process: Glycolysis converts glucose to pyruvate, which is then converted to lactic acid.

  • Inputs: Pyruvate and NADH.

  • Outputs: 2 ATP (low yield), 2 lactic acid molecules.

  • Characteristics: Anaerobic process.

2. Alcoholic Fermentation

  • Who: Yeast and bacteria.

  • Location: Cytoplasm.

  • Process: Glycolysis converts glucose to pyruvate, which is further converted to ethanol and carbon dioxide.

  • Inputs: Pyruvate and NADH.

  • Outputs: 2 ATP (low yield), ethanol, CO2.

  • Characteristics: Anaerobic process.

Applications of Fermentation

  • Lactic Acid Fermentation Products: Yogurt, sauerkraut, kimchi, cheese.

  • Alcoholic Fermentation Products: Breads, wine, beer.

Comparison of Respiration Types

  • All respiration types include glycolysis and produce ATP.

  • Aerobic Respiration: Requires oxygen, yields up to 34 ATP.

  • Anaerobic Respiration (Fermentation): Occurs without oxygen, yields only 2 ATP.

  • Efficiency comparison: Aerobic is much more efficient than fermentation.