genotype


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genotype

(jēn`ətīp'): see geneticsgenetics,
scientific study of the mechanism of heredity. While Gregor Mendel first presented his findings on the statistical laws governing the transmission of certain traits from generation to generation in 1856, it was not until the discovery and detailed study of the
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.

genotype (and phenotype)

the unique collection of genes an individual receives from both parents as a result of cell division (meiosis) and fusion of the ovum and sperm (fertilization). All these genes have the potential to determine, or help determine, characteristics of the individual, but not all will in fact exert an influence since they are received from both parents and the gene for a characteristic, e.g. eye colour, from one parent may be dominant over that from the other parent. The genotype therefore expresses genetic potential, and even though genes may not be expressed in the individual they will be passed on to the offspring.

While the genotype is the total genetic potential of the individual, the phenotype is the actual expression of the genes as the individual. The phenotype therefore describes the pattern of genes that have influenced the development of the individual, e.g. the gene for the individual's eye colour, but not for the eye colour not exhibited, though still carried in the genotype.

Genotype

 

the sum total of all the genes localized in the chromosomes of a given organism. In a broader sense, the genotype is the sum total of all the hereditary factors of the organism, both nuclear (genome) and nonnuclear, or extrachromosomal (that is, cytoplasmic and plastid hereditary factors). The term was introduced by the Danish biologist W. Johannsen in 1909.

The genotype is the carrier of hereditary information, transmitted from generation to generation. It is the system that controls the development, structure, and vital activity of the organism, that is, the sum total of all the characteristics of the organism—its phenotype. The genotype is an integral system of interacting genes, so that the expression of each gene depends on the genotypic environment in which it is located. For example, the red coloration of the blossoms in some varieties of the sweet pea arises only during the simultaneous presence in the genotype of dominant alleles of two different genes, whereas separately each of these alleles causes a white coloration of the blossoms. The interaction of the genotype with the complex of factors of the internal and external environment of the organism cause a phenotypic manifestation of characteristics. The coloration of the fur of rabbits of the so-called Himalayan line serves as an example of the influence of the environment on phenotypic manifestation of genotype. Although they have one and the same genotype, these rabbits when raised in cold temperatures have black fur; when raised in moderate temperatures they have the Himalayan coloration (white with black noses, ears, feet, and tail). When raised in hot temperatures they have white fur. The offspring of these three groups of animals inherit not one immutable coloration of fur but, rather, the ability to produce a particular coloring depending on environmental conditions. Thus, in a general sense, it is more correct to say that the genotype determines the inheritance not of concrete traits but of the norm of reaction of the organism to all possible conditions of the environment. Some genes are in an active state at certain times in an individual’s development, while other genes may become active at other times; therefore, in ontogenesis the genotype functions as a changeable mobile system.

The term “genotype” is sometimes used in a much narrower sense to denote simply groups of genes or even individual genes whose inheritance is being studied. For example, the splitting offspring of the monohybrid cross AA x aa are commonly said to have genotypes AA, Aa, and aa, and the possible differences based on other genes between corresponding individuals (or groups of individuals) is disregarded.

V. I. IVANOV

genotype

[′jē·nə‚tīp]
(genetics)
The genetic constitution of an organism, usually in respect to one gene or a few genes relevant in a particular context.
(systematics)
The type species of a genus.
References in periodicals archive ?
Genotype by environment for disease resistace and other importante agronomic traits supporting the indication of common bean cultivars.
Among other factors, this low productivity can be explained by the prevalent cultivation of the species in small properties, as well as by the lack of accurate genotype recommendations for specific microregions (MARTINS et al., 2016).
A report from several central European countries suggested that, compared to genotype D, genotype A was more often found in older patients, whereas genotype D predominated in younger ones (22).
Allele type and related lipid contents of each carrier family showed significant (p = 0.04) increased levels of triglyceride in CC genotype compared to CG and GG genotypes.
where Yij is the mean response of the i-th genotype (i = 1,2, ..., G genotypes) at j-th environment (j = 1,2, ..., E environments); [mu] is the overall mean of the trials; gi is the effect of the genotype i, i = 1,2...g; aj is the effect of the environment j, j = 1...a; [lambda]c is the c-th singular value (scalar) of the original interaction matrix (denoted by GE); Otic is the element corresponding to the i-th environment at c-th singular line vector of the GE matrix; [gamma]jc is the element corresponding to the i-th genotype in the c-th singular column vector of the GE matrix; [delta]ij is the noise associated with the term (GE)ij of the classical interaction of genotype i with j environment interaction; [epsilon]ij is the mean experimental error.
The knowledge of causative HBV genotype is of immense importance from both clinical and epidemiological points of view.
For stress tolerance index, the genotype IUB-212 performed best with highest mean value (3.66) followed by VH-144 (3.64) and NIAB-111 (3.41) depicting that these genotypes were drought tolerant whereas genotype CRS-456 performed poorest with lowest mean value (0.28) followed by S-12 (0.3) and IUB-222 (0.4).
Samples positive in qualitative detection of HCV by CLIA were further processed for viral load estimation and genotype analysis.
The Linear Array HCV Genotyping Test (Roche) was used to determine the genotype (1-6) of each HCV sample from patients, according to the manufacturer's instruction.
Leaf-level gas exchange varies among loblolly pine genotypes, and it has been implicated as a potential measure of genotype success [13-15].
Ternary genotype code, Line-dot method, Modified Punnett squares, Ternary coded genotype probability groups, Line-dot hexagon, Genotype hexagon, Genotype to phenotype hexagon, Phenotype to genotype square.