Narrow Results

The relationship between the organism's growth and its geometrical form was suggested by many ancient and modern thinkers. Many other factors influence growth and replication. All these numerous factors, such as biochemical, physical, work in cooperation. In this paper, we consider the impact of geometrical and physical characteristics of organisms, such as surface, volume and geometrical form, on organisms' growth and replication. The mathematical basis of our study is the growth equation, which describes growth from the physical perspective. First, we model the growth of cells by different shapes, and compare theoretical results to experimental data. We discover that the growth dependencies produced by the growth equation fit experimental data very accurately if we take into account two considerations. First, the cell, or a multicellular growing object, can switch into a replication phase before its physical growth potential is exhausted. Second, the inflow of substance through a unit of the membrane's surface increases during growth, because the cell's growing volume allows it to process more nutrients. Then, we consider overgrowth from the physical perspective, introduce the notion of a growth ratio as an important geometrical characteristic of the growth and overgrowth processes, and generalize our findings.

We present significantly advanced studies of the previously introduced physical growth mechanism and unite it with biochemical growth factors. Obtained results allowed formulation of the general growth law which governs growth and evolutional development of all living organisms, their organs and systems. It was discovered that the growth cycle is predefined by the distribution of nutritional resources between maintenance needs and biomass production. This distribution is quantitatively defined by the growth ratio parameter, which depends on the geometry of an organism, phase of growth and, indirectly, the organism's biochemical machinery. The amount of produced biomass, in turn, defines the composition of biochemical reactions. Changing amount of nutrients diverted to biomass production is what forces organisms to proceed through the whole growth and replication cycle. The growth law can be formulated as follows: the rate of growth is proportional to influx of nutrients and growth ratio. Considering specific biochemical components of different organisms, we find influxes of required nutrients and substitute them into the growth equation; then, we compute growth curves for amoeba, wild type fission yeast, and fission yeast's mutant. In all cases, predicted growth curves correspond very well to experimental data. Obtained results prove validity and fundamental scientific value of the discovery.