A very clear explanation of the importance of bioenergetics in the origin of life and the evolution of the eukaryotes, and a detailed discussion of the possible role of endosymbiosis in the evolution of complex organisms, sex, apoptosis and aging. A lot has happened since I learned the Krebs cycle, and just the update, including the extraordinary appearance of ATP synthase, along with the discussion relating biochemistry to evolution makes the book worthwhile. Dr. Lane's imagined trip through a mitochondrion, shrinking us to the size of an ATP molecule, to explain chemiosmotic coupling is inspired.