word "phenotype" is of Greek origin and is translated (literally) "discover", "I am".What is the practical significance of this concept?
What is phenotype?Determination
Under the phenotype should be understood set of characteristics that are inherent to the individual at a particular stage of development.Formed on the basis of this set of genotype.For diploid organisms characteristic manifestation of the dominant genes.Determine exactly what the phenotype should be talking about the combination of internal and external signs of the body, which were acquired in the process of individual development (ontogeny).
General
Despite the fairly precise definition of what a phenotype, its concept has a number of uncertainties.Most of the structures and molecules that are encoded by the genetic material, not found in the appearance of the body.Thus they are a part of the phenotype.An example would be the phenotype of human blood.In this regard, according to several authors, the definition should also include the characteristics that can be obtained with the use of diagnostic, medical or technical procedures.More radical may contain further expansion of learned behavior and, if necessary, and the impact on the environment of the organism and other organisms.So, for example, bits and dam beavers can be taken for their phenotype.
Key Features
determine what is the phenotype, we can speak of a "rushing" the genetic information to meet environmental factors.The first approach should be considered two characteristics:
- dimensionality phenotype.This attribute indicates the number of lines of "removal", which characterizes the number of environmental factors.
- second sign indicates the level of sensitivity phenotype to the environment.It called this degree - range.
Together, these characteristics suggest the richness and variety of the phenotype.The multidimensional set of individual characteristics, the more sensitive features and the farther they are from a genotype, the richer.For example, when compared to the phenotype of the bacteria, roundworm, frog, man, "wealth" in the chain increases.This means that the phenotype of human richer.
Background
In 1909 Wilhelm Johannsen (Danish scientist) for the first time - in conjunction with the concept of genotype - phenotype proposed definition.This allowed to distinguish heredity from the result of its implementation.The idea of the differences can be traced in the works of Mendel, and Weismann.The latter is different from somatic and reproductive cells in multicellular organisms.The resulting set of chromosomes from their parents is contained in the cell nucleus.Chromosomes are complex genes specific to a particular species in general and in particular from an organism.Genes contain information about proteins that can be synthesized, and the mechanisms that are, in fact, define and regulate the synthesis.What if this happens?During ontogeny activating genes and those synthesized proteins that they encoded.The result is the formation and development of the properties and characteristics of the organism, constituting its phenotype.In other words, it turns a kind of "product" of the implementation of the genetic program contained in the genotype.
influence of external conditions on the development of individual features
It should be noted that the genotype is not unique factor that determines the phenotype.In varying degrees, the formation of the aggregate of individual features will depend on the host environment, ie by external factors.In different conditions phenotypes are sharply opposed.For example, the species of butterfly "arashniya" annually produces two offspring.Those individuals, who emerged from overwintered pupae (spring), are very different from those that appeared in the summer.It can also vary and the phenotype of the plant.For example, in an open space bushy pine, and in the forest - tall and slender.In water buttercup leaf shape depends on where it resides - in the air or in the water.
Relations between phenotypes and genotypes
ability to change, which is provided genetic program, called the norm of reaction.As a rule, the more varied the conditions in which dwells view, the wider the norm.In the case where the environment is very different from that to which the form is adapted violation occurs in developing organisms, and they die.The signs of phenotype is not always reflected recessive alleles.But they are saved and can move on to the offspring.These data allow you to better understand the evolutionary process.In natural selection involves only phenotypes offspring also transmitted further and remain in a population of genotypes.Cooperation is not confined to relationships recessive and dominant alleles - many genes interact with each other.
