Аннотация:Membrane fragments that do not form vesicles were separated from the alga Chlamydomonas reinhardtii. These membrane sheets have a permanent electric dipole moment, so may be oriented in an electric field. The oriented membranes were immobilized in gel. We studied the electric signals upon laser flash excitation under different circumstances. The experiments showed that these membrane fragments contain mainly photosystem I units and they preserve their activity to a high percentage. The relatively easy preparation and large electric signals (in the range of 50 mV) make the system excellent for studying charge motion related to the excitation of photosystem I.