Chemical rearrangement and partial substrate oxidation generate:

Operational definition

Energy-conversion mechanism.

The conversion of chemical free energy through internally balanced oxidation and reduction of a substrate or substrate-derived intermediates, without dependence on an external respiratory acceptor.

Its essential functions are:

Item 18 classifies the organism’s metabolic mode; item 23 identifies the corresponding energy-conversion process. Reaction-center systems and retinal-based rhodopsins are the two major evolved forms of biological light-energy conversion, while microbial electron transport conserves chemical-redox energy in ion gradients and other energetic intermediates. (PubMed Central (PMC))