Basics of Anaerobic Respiration
What is anaerobic respiration?
What kind of cells perform lactic acid fermentation?
Muscle cells and certain bacteria (like Lactobacillus).
Which organism commonly performs alcoholic fermentation?
Yeast.
What is an anaerobe?
An organism that can live without oxygen.
What bacterium causes tetanus (lockjaw)?
Clostridium tetani.
Where does anaerobic respiration occur in the cell?
In the cytosol.
What is the main product of lactic acid fermentation?
Lactic acid (lactate).
What are the two main products of alcoholic fermentation?
Ethanol and carbon dioxide.
What is an obligate anaerobe?
An organism that cannot survive in oxygen.
How does C. tetani cause muscle spasms?
It releases toxins that interfere with normal muscle contractions.
Name the two phases of anaerobic respiration?
Glycolysis and Fermentation.
What happens to lactic acid when oxygen becomes available again?
It is oxidized back to pyruvate and enters the aerobic pathway.
What compound forms between pyruvate and ethanol?
Acetaldehyde.
What is a facultative anaerobe?
An organism that can use either oxygen or fermentation pathways.
Why is Saccharomyces cerevisiae important in food production?
It's used in baking, brewing and winemaking through fermentation.
How much ATP is produced per glucose molecule?
2 ATP.
Why do muscles switch to lactic acid fermentation during intense exercise?
Because oxygen supply is limited, and the cells still need ATP quickly.
How does yeast make bread rise?
It produces CO₂ during fermentation, forming air bubbles that expand the dough.
Give one example of an obligate anaerobe.
Clostridium tetani.
How does fermentation help create probiotic foods like yogurt?
It supports beneficial bacteria that converts sugars into acids and aid digestive health.
Why does aerobic respiration produce more ATP than anaerobic respiration?
Because oxygen allows complete oxidation of glucose in the mitochondria, producing much more ATP.
How do bacteria like Lactobacillus bulgaricus help make yogurt?
They ferment lactose into lactic acid, thickening the milk and giving it a tart flavor.
Compare alcoholic and lactic acid fermentation in terms of products.
Alcoholic fermentation produces ethanol + CO₂, while lactic acid fermentation produces lactic acid only.
How does yeast act as a facultative anaerobe?
It performs aerobic respiration when oxygen is present but switches to alcoholic fermentation when oxygen is absent.
Explain one biotechnological or medical use of fermentation.
Used in producing antibiotics, biofuels or insulin and in biotech cultures where oxygen can't be used.