at complex 4: Cytochrome oxidase utilizes electrons transferred in the etc to synthesize water using half molecular oxygen( from respiration).
At complex 5: The protons tha create a proton gradient outside in the cytosol of mitochondria reenter the matrix here at complex 5 atp synthase. The energy of proton is thus utilisized to convert... Adp+p---->atp.
This is oxidative phosphorylation where oxidation( electrons+1/2o2---->h2o) n phosphorylation(adp +p---> atp) are clubed to release atp
