Synchronously grown cultures of dark-adapted Chlorella fusca cells were illuminated with single flashes and series of flashes from a xenon discharge tube and a nitrogen laser, and the photosynthetic oxygen evolution was measured polarographically under the condition of photosynthetic saturation at ambient temperature. The mechanical and electrical construction of the Joliot-type oxygen polarograph is described. Kinetic analysis of the amperometric signal obtained after single flashes revealed that the diffusion of the oxygen molecules through the thylakoid membrane is the controlling process of the response of the electrode and leads to a lag phase at the beginning of the rise of the signal. The oscillation of the oxygen evolution produced by series of flashes is damped much more with laser flashes. This is explained in terms of the side carrier model of the losses in the oxygen production, assuming that photoactivation of the side carrier by visible light leads to less damped oscillations with xenon flashes. These experiments indirectly corroborate the validity of the side carrier model.
ASJC Scopus subject areas
- Physics and Astronomy(all)