The thermodynamics of life are taking shape

Uncovering the scientific laws that govern our world is often considered the “holy grail” by scientists because such discoveries have far-reaching implications. In an exciting development from Japan, scientists have shown how to use geometric representations to encode the laws of thermodynamics and apply those representations to make generalized predictions. This work can greatly improve our understanding of the theoretical limitations that apply in chemistry and biology.

While living systems are bound by the laws of physics, they often find creative ways to use those rules in ways that nonliving physical systems rarely can. For example, every living organism finds a way to reproduce itself. At a fundamental level, this relies on autocatalytic cycles, in which a given molecule can stimulate the production of identical molecules, or a series of molecules can produce each other. The volume of the compartment in which the molecules are located increases. However, scientific knowledge lacks a complete thermodynamic account of such self-replicating processes that would allow scientists to understand how living systems can arise from non-living objects.

Well, in two related articles published in Physical Review Researchresearchers at the Institute of Industrial Science at the University of Tokyo used a geometric technique to characterize the conditions corresponding to the growth of a self-replicating system. The guiding principle is the famous second law of thermodynamics, which states that entropy – generally understood as disorder – can only increase. However, an increase in order may be possible, e.g. B. when a bacterium takes up nutrients to divide into two bacteria, but at the cost of increased entropy elsewhere. “Self-replication is a hallmark of living systems, and our theory helps explain the environmental conditions to determine their fate, whether they grow, shrink, or equilibrate,” says senior author Tetsuya J. Kobayashi.

The main finding was to represent the thermodynamic relationships as hypersurfaces in a multidimensional space. Then researchers could study what happens when different operations are performed, in this case using the Legendre transform. This transformation describes how a surface should be mapped into another geometric object with significant thermodynamic importance.

“The results were obtained solely on the basis of the second law of thermodynamics that total entropy must increase. Therefore, ideal gas assumptions or other simplifications about the nature of the interactions in the system were not required,” says first author Yuki Sughiyama. Calculating the rate of entropy production can be crucial for evaluating biophysical systems. This research may help put the study of the thermodynamics of living systems on a more solid theoretical footing, which may improve our understanding of biological reproduction.

The articles appear in Physical Review Research as “Hessian geometric structure of chemical thermodynamic systems with stoichiometric constraints” and “Chemical thermodynamics for growing systems”.

Provided by Institute of Industrial Science, The University of Tokyo (UTokyo-IIS)