CELLULAR RESPIRATION

ANAEROBIOSIS

•ANAEROBIOSIS is the process of anaerobic respiration or breakdown of glucose with the production of energy in the absence of oxygen.

ANAEROBIOSIS
in plants

•In PLANTS, anaerobic respiration is also known as fermentation

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–occurs in germinating seeds, storage organs like tuber, fruits or roots when the supply of oxygen is not enough.

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–the ethanol produced is poisonous to cells and kills the cells.  In fermentation, the yeast can withstand about 10% of alcohol in the medium

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–Total ATP produced in yeast is two moles of ATP per mole of glucose and the alcohol still contains energy.  In plants, this is not the usual way to obtain energy.

 

Initially, glycolysis takes place as in aerobic respiration in which pyruvate is produced.

Krebs cycle cannot occur. 

When there is no oxygen, oxidative phosphorylation cannot occur.  There is no NAD+ as it is in the form of NADH and not oxidised. Pyruvate cannot undergo oxidative decarboxylation to form acetyl coenzyme A to enter the Krebs cycle.

Ethanol is produced.

The pyruvate accumulates and stimulates the production of enzyme that converts it to acetaldehyde and CO2. 

The acetaldehyde is then converted into ethanol (alcohol).