Question

Oxidative phosphorylation is achieved through chemiosmotic coupling, which turns chemical energy into osmotic potential energy that is used to synthesize the energy “currency” of the cell (ATP). This process is divided into stage 1 (electron transport chain) and stage 2 (ATP synthase). Answer the following questions about each stage:

1. In stage 1, what is the energy source used to form the proton gradient across the inner membrane and what is the principal carrier of this energy source?
2. In stage 2, the total potential energy (proton-motive force) stored in the proton gradient used to power ATP synthase is composed of two components. What are these two components?

Answer 1

1 ) Energy from NADH and FADH₂ from Kreb's cycle are transfered to ATP. Energy from NADH is a source, used to form proton gradient across inner membrane . Principle carrier of energy sources are coenzyme G and cytochrome C.

2 ) Proton gradient are used to generate chemiosmotic potential, proton motive force. This potential energy is used for ATP synthesis by oxidative phosphorylation. 2 components of the proton motive forces are membrane potential and gradient of proton concentration.