Fermentation Flashcards
What 3 molecules can pyruvate become?
Ethanol, lactate, or acetyl-CoA
What is the purpose of fermentation?
To regenerate NAD+ under anaerobic conditions
Why is it necessary to regenerate NAD+?
The amount of NAD+ and NADH is constant in the cell, and GAPDH requires an NAD+
What happens if there is no NAD+ in the cell?
GAPDH can’t function and glycolysis stops, and the cell can’t continue producing some ATP under anaerobic conditions
How is ethanol produced from pyruvate?
2 step reaction. A carboxyl group gets cleaved off pyruvate and released as CO2 and acetaldehyde. Acetaldehyde gets reduced by NADH to form ethanol
Which enzyme catalyzes step 2 of ethanol fermentation?
Alcohol dehydrogenase
How is lactate produced from pyruvate?
Pyruvate is reduced by NADH to form lactate
Which enzyme catalyzes the formation of lactate from pyruvate?
Lactate dehydrogenase
Is lactate fermentation reversible?
Yes, it will eventually reach equilibrium
What happens if lactate fermentation reaches equilibrium?
It can’t be driven forward anymore, so glycolysis also stops
How do muscle cells prevent lactate fermentation from reaching equilibrium?
It is exported into the blood along with a hydrogen
How does lactate fermentation contribute to the Bohr effect?
A hydrogen is released into the blood by the lactate cotransporter along with a lactate. This lowers the blood pH and causes hemoglobin to change into the T state and release oxygen so it can be used by the muscles
What is the Cori cycle?
The lactate exported into the blood by the muscle gets converted back to pyruvate and sent through gluconeogenesis in the liver. The glucose is exported back into the blood for the muscle to send through glycolysis
