The CoRR hypothesis for genes in organelles.

•A bioenergetics context is described for the endosymbiont hypothesis for the origin of bioenergetics organelles.•Cytology, genetics and biochemistry demonstrate DNA in chloroplasts and mitochondria but not its function or the reason for its persistence in evolution.•The CoRR Hypothesis – Co-location for Redox Regulation –is described and reviewed.•CoRR states that genes found within chloroplasts and mitochondria are the subsets of endosymbiont genes whose protein products have always exerted direct redox regulatory control over expression of their own genes, while this control requires that the genes subject to regulation remain, with their protein products, within a single membrane-bound compartment.•Cells –the topology and anisotropy of energy-transducing membranes.