What Is life? Rethinking Biology in Light of Fundamental Parameters.

Defining life is an arduous task that has puzzled philosophers and scientists for centuries. Yet biology suffers from a lack of clear definition, putting biologists in a paradoxical situation where one can describe at the atomic level complex objects that remain globally poorly defined. One could assume that such descriptions make it possible to perfectly characterize living systems. However, many cases of misinterpretation put this assumption into perspective. In this article, we focus on critical parameters such as time, water, entropy, space, quantum properties, and electrostatic potential to redefine the nature of living matter, with special emphasis on biological coding. Where does the DNA double helix come from, why cannot the reproduction of living organisms occur without mutations, what are the limitations of the genetic code, and why do not all proteins have a stable three-dimensional structure? There are so many questions that cannot be resolved without considering the aforementioned parameters. Indeed, (i) time and space constrain many biological mechanisms and impose drastic solutions on living beings (enzymes, transporters); (ii) water controls the fidelity of DNA replication and the structure/disorder balance of proteins; (iii) entropy is the driving force of many enzymatic reactions and molecular interactions; (iv) quantum mechanisms explain why a molecule as simple as hydrocyanic acid (HCN) foreshadows the helical structure of DNA, how DNA is stabilized, why mutations occur, and how the Earth magnetic field can influence the migration of birds; (v) electrostatic potential controls epigenetic mechanisms, lipid raft functions, and virus infections. We consider that raising awareness of these basic parameters is critical for better understanding what life is, and how it handles order and chaos through a combination of genetic and epigenetic mechanisms. Thus, we propose to incorporate these parameters into the definition of life.