Question

1. describe what uncouplers do to the P/O ratio in an actively respiring mitochondrion.

Answer 1

An uncoupler or uncoupling agent disrupt the oxidative phosphorylation process going on inside the mitochondria by dissociating the ATP synthesis reaction from electron transport chain. Which means although enrrgy will be expended released from oxidation of glucose and other biomolecules but it will not be creating any proton motive force hence no ATP will be generated (phosphorylation of ADP).

On the other hand P/O ratio defines the amount of ATP generated by reduction of one oxygen atom. Since uncoupler will result in dissociating the phosphorylation from electron transport chain. It means inside an actively respiring mitochondria while oxygen atom will be consumed; i.e. reduced but no phosphorylation of ADP into ATP will be happening and the P/O ratio will be less than in comparision to when uncouplers will not be there.