the functional changes observed in different
conditions relate to changes in their organiza-
tion? Recent developments in cryo–electron
tomography hold the promise to provide de-
tailed maps of the complexes in the membrane
( 97 , 98 ). These results, combined with func-
tional in vivo data and advanced calculations
and modeling, should enable us to understand
the various processes in physiological condi-
tions. Highly sophisticated x-ray free electron
laser experiments on PSI and PSII crystals will
permit observation of the photosystems in
action, providing new insights for, e.g., elec-
tron transfer and water splitting ( 99 – 101 )
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