Alternative Metabolic Pathways

7.4  Fermentation

Fermentation is the anaerobic breakdown of glucose, forming 2 ATP and a toxic by-product.


Fermentation summary


In animal cells during fermentation, lactate,is made as a waste product.

Although fermentation produces only 2 ATP molecules per glucose, it is essential as a quick source of ATP energy for cells when they can't get enough oxygen. 

During vigorous exercise, muscle cells can run low on oxygen. When this happens, fermentation occurs and lactate builds up in the muscle tissue.

The increase in lactate changes the pH, creating the "burn" associated with exercise.


Microorganisms and Fermentation

Bacterial fermentation produces either lactate (ex. yogurt) or alcohol (ethanol) + CO2.

Yeast are well known microorganisms that produce alcohol and CO2 during fermentation.

Ethanol production is critical for the making of beer, wine and a gasoline substitute.

It's the alcoholic fermentation of bread made with yeast and sugar that causes it to rise. The dough rises as tiny bubbles of carbon dioxide gas are released by the fermenting yeast cells. The alcohol that is produced evaporates during baking.


 Toggle open/close quiz question

How does fermentation benefit humans?
    a.yeast use fermentation to produce alcohol can be used to make ATP when our muscle cells run out of oxygen is used by bacteria to make yogurt is used by microorganisms to make ethanol to fuel our automobiles
    e.all of the answers are correct


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