Anaerobic respiration Fermentation Anaerobic respiration

Anaerobic bacteria Use inorganic molecules as their electron acceptors Nitrates sulfate

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

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

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)

Fermentation Advantages: Disadvantages: 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.

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

Fermentation Input: glucose and 2 ATP (glycolysis) 2 pyruvate  2 lactate 2 alcohol and carbon dioxide and 2 ATP

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