Tuesday, April 19, 2011

Anaerobic Respiration (Fermentation)

1. Anaerobic respiration (fermentation):
    - respiration takes place in the absence of O2
    - occurs only in the cytoplasm.
    - produces: pyruvate, 2 NADH + 2 mol ATP 
    - pyruvate + NADH accumulate in cytoplasm

2. - pyruvate + NADH accumulate in cytoplasm
       --> causes tissues to run out of H acceptor (NAD+) - limited supply.
       --> glycolysis may not occur.
       --> need for an alternative H acceptor.
       --> pyruvate or acetaldehyde becomes the H acceptor.
       --> pyruvate can undergo both aerobic and anaerobic respiration.

3. In plants:
    - pyruvate undergoes alcohol fermentation --> produce ethanol,
    - occurs in roots of the plants (water logged conditions).

4. In animals:
    - pyruvate undergoes lactic acid fermentation --> produce lactic acid
    - occurs in the muscles during vigorous activity + strenuous exercise.

7. Fermentation products are used commercially.
    - Wine, methanol and formic acid are formed by alcohol fermentation.
    - Yogurt, cheese and soy sauce are formed by lactic acid fermentation.

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