Fermentation
Definition and meaning of Fermentation in chemistry.
Fermentation is an anaerobic metabolic process that extracts energy from carbohydrates without the use of oxygen or an electron transport chain. It relies on glycolysis to produce adenosine triphosphate and uses an endogenous organic electron acceptor to regenerate NAD+ from NADH.
In more detail
Because fermentation lacks oxygen as a final electron acceptor, the pyruvate generated during glycolysis cannot be fully oxidized in the mitochondria. Instead, it is reduced directly or indirectly by NADH, allowing glycolysis to continue producing a small amount of ATP. The two most common types are lactic acid fermentation and alcoholic fermentation. In lactic acid fermentation, common in mammalian muscle cells and certain bacteria, pyruvate is reduced directly to lactate. In alcoholic fermentation, utilized by yeast and some bacteria, pyruvate is decarboxylated to acetaldehyde and then reduced to ethanol and carbon dioxide. While less efficient than aerobic respiration, fermentation allows organisms to survive and generate energy in oxygen-depleted environments.
Key facts
| Field | Biochemistry |
|---|---|
| Formula | C2H5OH |
| Molar mass | 46.07 g/mol |
| Net ATP yield | 2 ATP per glucose |
| Common types | Lactic acid, alcoholic |
| Condition requirement | Anaerobic environment |
The production of bread relies on Saccharomyces cerevisiae yeast undergoing alcoholic fermentation, producing carbon dioxide gas bubbles that cause the dough to rise.
Frequently asked questions
Why do muscles burn during intense exercise?
During intense exercise, oxygen demand exceeds supply, forcing muscle cells to use lactic acid fermentation; the accumulation of lactate and associated protons contributes to muscle fatigue and a burning sensation.
Can humans survive solely on fermentation?
No, fermentation produces only a fraction of the ATP generated by aerobic respiration, which is insufficient to meet the high energy demands of complex human organs like the brain and heart.