The biochemical foundation for biogenesis of photo-autotrophy is investigated. The enzymatic machinery regulating chlorophyll and protein synthesis and assembly of multienzyme complexes are studied. Our goal is to understand the molecular principles for building the photosynthetic machinery. We make use of the etioplast as an experimental organelle system, to investigate chlorophyll dependent biogenesis steps. At present, chlorophyll-binding to Cytochrome b6f is investigated.