Living beings, which are in a quasi-stable condition (meta-stable) between unstable and neutrally stable, use only five types of nitrogenous bases and 20 amino acids selected naturally. A first-order approximation of the momentum equation derived based on the cyto-fluid dynamic theory reveals the reason why the molecular weight of purines and pyrimidines among the nitrogenous bases varies by only about 1. 5 times, although the variation principle for the energy conservation law cannot do so. Here, we take a higher order of the Taylor series for the unified momentum equation describing the deformation motions of biological molecules. Even-numbered terms such as the second and fourth show no other quasi-stable size ratios. However, odd-numbered terms result in other quasi-stable ratios. The three-fold variation of the molecular weights of amino acids will come from the third term of the Taylor series.
ASJC Scopus subject areas