Glossary of terms

     Phenotype is a set of characteristics inherent in an individual at a certain stage of development. The phenotype is formed on the basis of the genotype mediated by a number of external factors. In diploid organisms, dominant genes are manifested in the phenotype.

     Phenotype is a set of external and internal characteristics of an organism acquired as a result of ontogenesis (individual development). All clinically determinable characteristics of an individual: height, body weight, eye color, hair shape, blood type, etc. are phenotypic.

 

     Despite its strict definition, the concept of phenotype has some uncertainties. First, most of the molecules and structures encoded by genetic material are not visible in the appearance of an organism, although they are part of the phenotype. For example, this applies to human blood groups. Therefore, an expanded definition of phenotype should include characteristics that can be detected by technical, medical or diagnostic procedures. A further, more radical extension could include acquired behaviors or even the effects of an organism on its environment and other organisms.

 

       Phenotype can be defined as the "carrying" of genetic information to meet environmental factors. As a first approximation, we can talk about two characteristics of the phenotype:

a) the number of directions of the carry-over characterizes the number of environmental factors to which the phenotype is sensitive - the dimensionality of the phenotype;

b) the "distance" of the carryover characterizes the degree of sensitivity of the phenotype to a given environmental factor. Taken together, these characteristics determine the richness and development of the phenotype. The more multidimensional the phenotype and the more sensitive it is, the further the phenotype is from the genotype, the richer it is. If we compare a virus, a bacterium, roundworms, a frog, and a human, the richness of the phenotype in this series increases.

 

      The factors on which phenotypic diversity depends, the genetic program (genotype), environmental conditions, and the frequency of random changes (mutations), are summarized in the following relationship:

 

                                                         genotype + environment + random changes = phenotype