Question

Protons:

a) How is proton motive force connected to ATP synthase, electron transport and chemiosmosis?

b) Briefly describe what happens to the electrons and protons in the electron transport chain?

Answer 1

A. Electron transport train is a process in which electrons are transferred from one electron carrier to the other. The electron Carriers are arranged in increasing order of their redox potential. Electrons are transferred from the carrier with lower redox of potential which have lower affinity for electrons to the one with higher redox potential which have higher affinity for electrons. When electrons are transported from one electron carrier to the other, Carriers also pump protons from mitochondrial Matrix to intermembrane space. This protons are then pumped back into the mitochondrial matrix by ATP synthase enzyme. This creates a Proton gradient across the inner mitochondrial membrane. The proton gradient so formed is also called as Proton motive force. This leads to spinning of ATP synthase enzyme which then drives ATP synthesis by phosphorylating ADP. The process of formation of ATP by using electrochemical energy stored in Proton gradient is called as chemiosmosis.

B. During electron transport chain, electrons are passed on from one electron carrier do the other and are ultimately accepted by oxygen molecule to form water which is a byproduct of electron transport chain.

Protons are formed from the mitochondrial matrix to intermembrane space by electron Carriers and then back into the mitochondrial matrix by ATP synthase. Protons are helpful in creation of Proton gradient which is used as an energy source for the synthesis of ATP by ATP synthase.

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