Is there a ‘Hydrogen Atom’ of Biology?

The hydrogen atom is the smallest representation of a chemical element and considered to be the most complex form of matter that can be analytically calculated, i.e. understood from first principles, by quantum mechanics. Thus, it has become a paradigm for understanding the material world in the perspective of physicists and chemists. Such a minimal system that aids the development of fundamental theories and hypotheses, however, has not yet been identified in biology. To the contrary, life sciences have from their very beginnings dealt with incomprehensively complex systems, such as animals and plants, and only the past decades have allowed us to elucidate their molecular makeup and formulate quantifiable laws that can be, albeit often with disappointingly low statistical confidence, addressed by physical methods and technologies. Our very simple question, which is however extremely challenging to answer, is whether something like a minimal system, reminiscent of the hydrogen atom for physics and chemistry, could also be identified for biology – the smallest possible representation of a living cell (being by definition the smallest unit of life). By methods of molecular biology and biochemistry we try to identify fundamental functional units in proteins or nucleic acids, the combination of which allows a system to develop emergent behavior to the point of establishing essential features of life, such as metabolism, replication, and functional evolution. Using cutting edge biophysical methods, we analyze these functions on the single molecule level and thereby aim to formulate a canonical set of functions that would be required for matter to become alive, independent of the carbon-based representation of life on earth.