Question

26) Briefly describe, using words or simple diagrams, the chemiosmotic theory for coupling oxidation to phosphorylation in mitochondria. (5 pts)

Answer 1

The chemiosmotic theory for ATP production was proposed by Peter Mitchell.

According to this theory, electrons from NADH oxidation travel via electron carriers to the terminal electron acceptor. During the transport of these electrons, protons are translocated from mitochondrial matrix to the intermembrane space. This translocation creates a proton gradient which contributes to chemical gradient ( pH) and electrical gradient ( ) . The matrix becomes alkaline because of low protons and negative because of protons having positive charge move to the intermembrane space.These gradient together constitute the electrochemical gradient which exerts proton motive force to drive the movement of protons back into the matrix. The inner mitochondrial membrane is impermeable to protons, which as a result reenter the matrix via FoF1 particles ( ATP synthase) . The synthase utilizes the proton motive force exerted by protons to synthesize ATP from ADP and inorganic phosphate.