Genetic Linkage

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Genetic Linkage


the joint transfer of two or more genes from parents to offspring. Genetic linkage occurs because such genes reside on the same chromosome, that is, they belong to the same linkage group and therefore cannot be accidentally recom-bined in meiosis, which occurs in the inheritance of genes residing on different chromosomes.

Genetic linkage was discovered in 1906 by the English geneticists W. Bateson and R. Punnett, who discovered in experiments on the crossing of plants the tendency of some genes to transfer together, thus violating the law of the independent combination of traits. This tendency was correctly explained by T. H. Morgan and his associates, who discovered a similar phenomenon in their study of inherited traits in the fruit fly (Drosophila).

Genetic linkage is measured by the frequency at which crossover gametes or spores are formed by a heterozygote on jointly transferring genes. In these gametes or spores, the genes occur in new combinations rather than in the original combinations, owing to the crossing-over of those parts of the homologous chromosomes bearing the genes. In some bacteria, another measure of genetic linkage is the frequency of joint transmission by inheritance of various genes in conjugation, genetic transformation, and transduction. The extent of genetic linkage may vary among the sexes: it is generally greater in the heterogametic sex. Genetic linkage may even be complete, without crossing-over, in one of the sexes, for example, in male Drosophila or in female Asiatic silkworms (Bombyx morí). The extent of genetic linkage may also vary with the age of the parents and with temperature. In addition, it may vary in the presence of chromosomal rearrangement or of mutant genes that influence the extent of genetic linkage.


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The GM of Agra Professional Services Division, Mrs Dagmar Honsbein, said: "the genetic mapping of Swakara, would be the first step in a process to register the breed as uniquely Namibian.
But little genetic mapping has been done on many other crops, Johnson and Lillegard said.
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On the heels of early promises that genetic mapping would allow medical science to identify and prevent gene-based conditions, ACA and the corrections community will need to consider the ethical, legal and moral implications of this research.
Genetic mapping of Namibian animal species has been made possible through Affymetrix GeneChip technology locally.
Their topics include the high-resolution analysis of genomic copy number changes, identifying polymorphic markers for genetic mapping, the genetic mapping of complex traits, gene expression in mammalian cells, predicting protein function, elucidating gene function using genetically engineered mice, delivery systems for gene transfer, and an introduction to proteomics technologies for the genomics scientist.
Owning a massive amount of Internet Real Estate associated with DNA Sequencing, genetic mapping and personalized medicine can be a windfall for a biotechnology company that wants to control the space and capture the associated Internet search traffic," says Rob Monster, Chairman and CEO of Epik.
Current projects involving the collection include genetic mapping of Rhizobium found in association with alfalfa and other Medicago species from Egypt, Spain, and Tunisia.
Coverage includes the areas of gene discovery and the functional analysis of genes; the primary tools and sub-disciplines of genetic mapping, mRNA, protein and metabolite profiling; methodologies for exploring gene function analysis via transformation, mutation, protein function and gene expression; data management issues such as the expansion of plant genomics databases and bioinformatics analysis tools; the application and deployment of molecular plant breeding technology from the use of markers in breeding; development of genetically modified plants/crop species; analysis of existing populations for novel alleles; and gene/trait associations and genome sequencing.
The genetic mapping may help future research on these people, who the researchers suspect have a genetic mutation that creates a milder abnormality.
One can move directly from genetic mapping to identification of candidate genes, and the experimental process is reduced to PCR amplification and sequencing of exons and other conserved elements in the candidate interval.
Aim 1 of the proposed project will implement a novel genetic mapping design to systematically survey the mosquito population for common and rare genetic variants of strong effect against the human malaria parasite, Plasmodium falciparum.