Fermentation can take place aerobically or anaerobically in cells. Anaerobic fermentation occurs when there is not enough oxygen after glycolysis. Alcohol fermentation is a two-step process where pyruvate is converted to ethanol via acetaldehyde. Lactic acid fermentation directly reduces pyruvate to lactate without carbon dioxide release and causes muscle fatigue and pain in humans during low oxygen states.

1. Fermentation

3. Aerobic/anaerobic
• Takes place in the cytoplasm.
• Fermentation is what happens if there is an
absence of oxygen after glycolysis, either it
proceeds with the Krebs cycle(aerobic) or
fermentation(anaerobic).
*Anaerobic doesn’t mean no oxygen when involving cells it
just means there is not a sufficient amount of oxygen.

4. Alcohol fermentation
• Pyruvate is changed into ethanol in two steps.

5. STEP 1
• The release of CO2 from the pyruvate, which
is than converted into two carbon compound
acetaldehyde.

6. STEP 2
• Acetaldehyde is than reduced by NADH to
ethanol, which than regenerates the supply of
NAD needed for ethanol.

7. Lactic acid
fermentation

9. • Pyruvate is reduced directly by NADH to end
up making lactate as a waste product and no
release of CO2.

10. • Human cells make lactic acid when there body
is either low or lacking oxygen. The muscle
than begins to fatigue and feel painful.