Figure 4.

In 1961, Peter Mitchell published his landmark manuscript entitled “Coupling of Phosphorylation to Electron and Hydrogen Transfer by a Chemi-Osmotic Type of Mechanism.” In the last paragraph of this paper, he declares that transport and metabolism may be conceived of as the “same process.” We extended this idea to speculate that the H⁺ diffusion can be considered an “inanimate” step within evolution that couples to the “animate” metabolic formation of ATP from ADP.