Question

Can someone help clarify the ration of electrons to protons throughout the Electron Transport Chain and what is meant by four-four-two? I am confused whether it’s 1 e- for every two protons or a 1 to 1 ratio. Thank you

Answer 1

In electron transport chain electrons flows into a seroes of carriers which are arranged in increasing order of their reduction potential and ultimately are accepted by terminal electron acceptor. During flow of electrons; Protons are pumped into Inter membrane space (IMS). For every two electron Complex I pumps 4 protons into IMS, for every 2 electrons 4 protons are pumped by Complex III and for every two electrons 2 protons are pumped by Complex IV. This pumping of proton from these complex in response to flow of two electrons is termed as Four-Four-Two These pumped electron flow back into mitochondrial matrix through ATP synthase and produce ATPs.