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Cellular Respiration


Home | Key Terms/ Key Words | What happens before cellular respiration? | Glycolysis | Transition Reactions | Kreb's Cycle | The electron transport chain | Fermentation

Fermentation begins when there is not enough oxygen available to produce carbon dioxide and water in aerobic respiration.
 There are two types of fermentation, they are; lactic acid fermentation and alcoholic fermentation.
Lactic Acid Fermentation
Lactis acid fermentation is a anaerobic process where enzymes break glucose (sugar) into two lactic acid molecules, and they transfer energy to ATP.
C6H12O6 + 4ADP + 4Pi --- 2CH3CHOHCOOH + 4ATP
(Glucose)                 (Enzymes) (Lactic Acid)
Lactic acid fermentation provides a mechanism, where muscles can keep working when oxygen cannot reach them quick enough.
Micro-organisms such as bacteria use lactic acid fermentation to produce sauerkraut and buttermilk.
Example: In our bodies certain muscle cells, called fast twitch muscles, have less capability for storing and using oxygen than other muscles. When you run and these muscles run short of oxygen, the fast twitch muscles begin using lactic acid fermentation. This allows the muscle to continue to function by producing ATP by glycolysis.
Alcoholic Fermentation
Alcoholic fermentation is a anaerobic process where enzymes break down glucose into two molecules of ethanol and two molecules of carbon dioxide and transfer energy to ATP.
C6H12O6 + 4ADP + 4Pi --- 2C2H5OH + 2CO2 + 4ATP
(Glucose)             (Enzymes) (Ethanol)
Examples: Alcoholic fermentation is used in baking, to create the rising effect that bread has. It is also found in beer, wine, and other alcoholic beverages.


Ethanol (alcoholic) Fermentation in yeast.