Oxygen is critical for aerobic respiration explain its role with respect to ETS

Aerobic respiration involves processes like glycolysis, Kreb's cycle and electron transport system. It is an enzyme-mediated catabolic process in which energy is liberated. The organic substrate is broken down in a stepwise manner inside the living cells and in the process, oxygen acts as a terminal oxidant.

In complex IV of the electron transport system, the electrons move in the following way- cyt c₁ to cyt c, cyt c to cyt a and cyt a₃, cyt a and cyt a₃ to oxygen. Both cyt a and a₃ have two copper centers and both these function as cytochrome oxidase. They hand over electrons to oxygen which has the ability to diffuse them into mitochondria. The oxygen then converts to anionic form and combines with 2H⁺ to form metabolic water. This is how oxygen plays critical role in ETS.

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