Some Genetic Aspects of Physiological Variability

Summary

The seeming paradox of a relatively fixed genotype combined with a considerable degree of physiological variability among individuals of inbred strains of experimental organisms is discussed for investigators in nongenetic disciplines in terms of the concepts of physiological genetics.

It is postulated that the rate of synthesis of the primary product of each gene is variable, that the maximum and minimum limits of this rate are determined by the molecular configuration of the specific gene, and that the actual rates of synthesis within these limits at any given time are determined by environmental factors extrinsic to the gene itself. A system, as envisioned here, of environmental factors acting on variable rates of synthesis of gene products would lead to a considerable degree of physiological variability even among completely homozygous organisms.