Filed under: CELLULAR ENERGETICS | Tags: anaerobic respiration, ATP production, cell biology, ethanol fermentation, fermentation, lactic acid fermentation, MCAT, MCAT prep, NAD+, regenerate NAD+, skeletal muscle, undergraduate biology, yeast
This tutorial presents fermentation at a level appropriate for most undergraduate biology classes and the MCAT exam.
Fermentation allows glycolysis to continue in the absence of oxygen, yielding a small amount of ATP. During fermentation 2 electrons a proton are transferred from each NADH product of glycolysis to pyruvate or a derivative acceptor molecule to regenerate NAD+. NAD+ is used to continue glycolysis.
Byproducts of fermentation include lactate, butate and ethanol.
1. Fermentation is an energy yielding process because it allows glycolysis to continue in the absence of oxygen. Since a net amount of 2 ATP is produced by glycolysis, a net amount of 2 ATP is also produced by fermentation.
2. NAD+ is required to complete glycolysis. NAD+ must be present to accept hydrogen before any ATP can be produced.
3. During glycolysis two molecules of NAD+ are reduced to NADH.
4. During lactic acid fermentation pyruvate is reduced to lactic acid and NADH is oxidized to regenerate NAD+.
5. In lactic acid fermentation hydrogen atoms (along with two electrons) are added directly on to pyruvate converting it to lactic acid. Pyruvate is the terminal electron acceptor and lactic acid is the product.
TERMS TO KNOW
adenosine triphosphate (ATP)
lactic acid fermentation
nicotinamide adenine dinucleotide (NAD+ / NADH)
terminal electron acceptor
RELATED TOPICS (Note: These links will go active as videos appear online.)
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