The photosynthetic apparatus of purple bacteria is composed of light-h
arvesting complexes and reaction centres. Recent work on the structure
s of light-harvesting complexes combined with existing knowledge of th
e structure of the reaction centre now makes it feasible, for the firs
t time, to model the entire photosynthetic apparatus. Questions can be
asked about the functional implications of such a model in the light
of the most recent spectroscopic data.