1. Glycolysis:
* Glucose is broken down into two molecules of pyruvate. This process generates a small amount of ATP and NADH.
2. Fermentation:
* Without oxygen: Pyruvate cannot enter the mitochondria for further processing in the Krebs cycle and electron transport chain. Instead, pyruvate undergoes fermentation.
* Two main types of fermentation:
* Lactic acid fermentation: Pyruvate is converted to lactic acid. This is common in muscle cells during intense exercise when oxygen supply is limited.
* Alcoholic fermentation: Pyruvate is converted to ethanol and carbon dioxide. This is used by yeast and some bacteria for producing alcoholic beverages.
* NAD+ regeneration: Both types of fermentation regenerate NAD+ from NADH. This is crucial because NAD+ is essential for glycolysis to continue.
Overall Chemical Changes:
* Glucose is partially oxidized: Fermentation doesn't fully break down glucose like aerobic respiration. It produces less ATP per glucose molecule.
* Byproducts are produced: Lactic acid or ethanol are produced as byproducts of fermentation.
* NAD+ is regenerated: This allows glycolysis to continue producing a small amount of ATP even without oxygen.
Important Points:
* Fermentation is less efficient than aerobic respiration in terms of ATP production.
* Fermentation can be harmful if lactic acid builds up in tissues, leading to muscle fatigue and soreness.
* Fermentation is essential for many processes, including food production (bread, yogurt, cheese), alcoholic beverages, and biofuel production.
Let me know if you'd like more details on specific types of fermentation or its role in different organisms!
