Mechanism of Aerobic and Anaerobic respiration.

Oxidation of complex organic substances like glucose to release energy is called as Respiration.

The Glucose is broken down in to two molecules of pyruvate in cytoplasm by GLYCOLYSIS.

The fate of pyruvate depends on presence and absence of oxygen.

[1]. Aerobic condition (Presence of Oxygen):

The glucose is completely oxidised to form water and carbon di oxide.

Large amount of energy is released.

It involves "Krebs cycle" and "Electron Transport System [ETS], which takes place in mitochondrion.

[2]. Anaerobic condition (Absence of Oxygen):

In lower organisms like bacteria, the pyruvate undergoes reductive decarboxylation.

This leads to formation of ethyl alcohol and CO₂ .

It occurs in cytoplasm and yields very less energy.

Lactic acid formation is due to reduction reaction. It is seen in lactic acid bacteria and muscle cell of higher organism.

The lactic acid is formed by reduction of pyruvate to lactic acid.