Electrons return to the original reaction system after driving ion-gradient formation.
Primary result:
light → ion motive force → ATP
without net production of reducing equivalents from the cyclic pathway itself.
Operational definition
Electron-flow mode.
An electron-transfer pathway in which light-excited electrons pass through a series of carriers and ultimately return to the original reaction-center system.
Its principal energetic consequence is usually:
cyclic electron flow
→
ion gradient
→
ATP
It produces no obligatory net transfer of electrons to a terminal external acceptor and, by itself, does not produce net reducing power.