What is the purpose of converting Pyruvate to Lactate in animal muscle cells?
To re-oxidize/regenerate NAD. This allows Glycolysis to continue producing a small amount of ATP (2 molecules) even when oxygen is absent.
Describe the chemical change from Pyruvate to Lactate.
Pyruvate is reduced
This is catalyzed by the enzyme lactate dehydrogenase.
Is Lactic Acid fermentation reversible? How?
Yes. When oxygen becomes available again, Lactate is transported to the liver and converted back into Pyruvate. It then enters the Link Reaction or is converted to glucose/glycogen. This requirement for oxygen is called the Oxygen Debt.
How does the anaerobic pathway in plants/yeast differ from animals?
It involves an extra step: Decarboxylation. Pyruvate loses a CO2 molecule before being reduced.
so goes pyruvic acid - ethanal - ethanol
Is Alcoholic Fermentation reversible?
No
cannot be converted back to pyruvate
if ethanol conc builds up too high it becomes toxic and kills the cells
