Fermentation

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Fermentation

• Anaerobic respiration

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Anaerobic bacteria

• Use inorganic molecules as their electron
  acceptors
• Nitrates
• sulfate

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Fermentation

• Pyruvate is reduced by NADH
• Alcohol and carbon dioxide OR
• lactate

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Alcoholic fermentation

• Ex. Yeasts,
• produce ethyl alcohol and CO2
• Alcohol usually ends up killing the yeast.

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Lactic Acid Fermentation

• Ex. Animals, some bacteria and fungi
• NADH reduces pyruvate to lactate
• Muscle cells see this when oxygen is not
  delivered to the cells fast enough.
• Bacteria produce cheese, yogurt, important
  chemicals (isopropanol, acetic acid)

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Fermentation

• Advantages
• 2 ATP, use in certain animals in tissues
• Disadvantages
• Toxic to cells, upon build up it can change the
  pH and cause muscle fatigue.
• Oxygen debt amount of O2 needed to rid body of
  lactate, lactate goes to liver where it is
  converted back to pyruvate.

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Fermentation

• Efficiency
• 2 ATP 14.6 kcal
• Complete breakdown to CO2 and water - possible
  energy yield of 686 kcal
• 2.1
• Aerobic respiration 39 effieciency

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Fermentation

• Input glucose and 2 ATP (glycolysis) ?2
  pyruvate ?
• 2 lactate
• 2 alcohol and carbon dioxide and 2 ATP

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Metabolic pool

• Degradative reactions ? catabolism ? exergonic
• Ex. Glucose, fat, proteins can be used as energy
  sources as well and enter the metabolic pathway
• Synthetic reactions ?Anabolism ? endergonic
• Compounds that enter the pathways are oxidized to
  substrates that can be used for biosynthesis