Question

How many protons are pumped through each of the electron transport chain complexes?

Complex I =
Complex II =
Complex III =
Complex IV =

Answer 1

Complex I = 4 proton

Complex II = 0 proton

Complex III = 4 proton

Complex IV =2 proton

Step-by-step explanation:

In the process of conversion of
`NADH` to
`FADH_2` to
`ATP` total three complexes are involved that are the integral proteins of the inner mitochondrial membrane and are involved in interacting with the electron thereby releasing proton.

Complex I = Total four protons across the membranes

Complex II = It do not have sufficient energy to pump out proton.

Complex III = Total four protons across the membranes

Complex IV = Total two protons across the membranes

Answer 2

ETC or electron transport chain refers to an array of complexes, which transfer electrons from electron donors to electron acceptors through the processes of oxidation and reduction that takes place simultaneously. This electron transfer is coupled with the transfer of hydrogen ions or protons through the membrane that produces an electrochemical proton gradient, which drives the production of ATP.

In the process of ETC, four membrane-bound complexes have been determined in the mitochondria of which three of them acts as proton pumps. In complex I, four protons are translocated across the membrane, thus, generating a proton gradient.

In complex II, no protons are translocated through the intermembrane space, thus, the pathway does not contribute much to the entire electron transport chain. In complex III, a total of 4 protons are translocated, of which two reduce quinone to quinol and two are discharged from two molecules of ubiquinol. In complex IV, 8 protons are withdrawn from the mitochondrial matrix, however, of them only 4 are translocated across the membrane, thus taking part in the proton gradient.