1. ANAEROBIC CELLULAR RESPIRATION: FERMENTATION

2. RECALL:
Cellular Respiration: the process of using glucose to make energy (ATP) for the cell.
Aerobic Cellular Respiration (Requires Oxygen), 2 steps
On average 30 ATP
Glycolysis
Oxidative Respiration
Location
Cytosol
Mitochondria
Reactant(s)
Glucose
Pyruvate + Oxygen
Products
Pyruvate
Carbon Dioxide + Water
Energy
2 ATP
28 ATP

3. ENERGY transfer between enzymes, other molecules
Aerobic Cellular Respiration (requires oxygen)
enzymes
6O2 + C6H12O CO2 + 6H2O
oxygen glucose carbon dioxide water
ENERGY transfer between enzymes, other molecules
ADP + Pi
ATP

4. WHAT IF THERE’S NO OXYGEN?
Some organisms can survive with little or no oxygen in their environments!
For example, microorganisms in
The bottom of a swamp
Sewage treatment plants
Pickling food jars
Contaminated canned goods
The human gut
And many more!!!
Gangrene – death of tissue due to a bacterial infection or circulatory problems.

5. CELLULAR RESPIRATION WITHOUT OXYGEN
Glucose
ANAEROBIC CELLULAR RESPIRATION
“Anaerobic:” – without oxygen
FERMENTATION
One of the types of anaerobic cellular respiration
Glucose molecule undergoes glycolysis as usual
2 Pyruvate and 2 ATP molecules are made
Pyruvate cannot undergo oxidative respiration because it requires oxygen.
The pyruvate molecule is broken down by a fermentation reaction.
Two common fermentation reactions:
Alcohol fermentation
Lactic acid fermentation
2 ATP
Cytosol
2 Pyruvate
Mitochondria

6. 2. LACTIC ACID FERMENTATION
1. ALCOHOL FERMENTATION
Occurs in the cytosol
Yeast – common microorganism that undergoes alcohol fermentation.
Each pyruvate is broken down into carbon dioxide and ethanol (an alcohol).
C3H6O3
Pyruvate
CO2
Carbon Dioxide +
C2H6O
Ethanol
2. LACTIC ACID FERMENTATION
Occurs in the cytosol
Can take place in human muscle cells during vigorous exercise
Each pyruvate is converted to lactic acid.
C3H6O3
Pyruvate
CO2
Carbon Dioxide +
C2H6O
Ethanol

7. FOOD, DRINK, AND FERMENTATION
Yeast has been used for alcohol fermentation by humans since 7000BC (for over 9000 years)!
Bread
First step is to create a “starter” which will activate yeast to start creating carbon dioxide and ethanol.
Either add baker’s yeast and flour to warm water.
Make a flour & water mixture and let it sit out. Yeast from the air will colonize the mixture.
Add other ingredients and let the dough “rise.”
Beer
Brewers mix together water and a starch source (like malted barley), add yeast, and add flavouring such as hops.