Cytochrome c fulfills a central role in biological electron transport. This book draws together information from diverse disciplines in order to provide a common base for further research. The comprehensive treatment of this subject does not neglect to show the diversity of biological respirations and photosyntheses. But it also defines their unifying principles. This overview presents the evolutionary relatedness in bioenergetic systems. Such systems are discussed at the experimental level with emphasis on the interpretation of results and the methodological approaches used. No other text provides a broad survey of this central area of biology. Researchers on cytochrome c are presented with information on the impact and importance of other disciplines on their area of investigation. Advanced students gain a balanced account of biological electron transport and will be encouraged to seek new directions of research.