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Polymorphisms can be identified in the laboratory using a variety of methods. Many methods employ PCR to amplify the sequence of a gene. Once amplified, polymorphisms and mutations in the sequence can be detected by DNA sequencing, either directly or after screening for variation with a method such as single strand conformation polymorphism analysis.
Since all polymorphism has a genetic basis, genetic polymorphism has a particular meaning: Genetic polymorphism is the simultaneous occurrence in the same locality of two or more discontinuous forms in such proportions that the rarest of them cannot be maintained just by recurrent mutation or immigration, originally defined by Ford (1940).
Genetic variation is the difference in DNA among individuals [1] or the differences between populations among the same species. [2] The multiple sources of genetic variation include mutation and genetic recombination. [3] Mutations are the ultimate sources of genetic variation, but other mechanisms, such as genetic drift, contribute to it, as ...
A single nucleotide polymorphism (SNP) is a difference in a single nucleotide between members of one species that occurs in at least 1% of the population. The 2,504 individuals characterized by the 1000 Genomes Project had 84.7 million SNPs among them. [ 2 ]
The OMIM database describes the association between polymorphisms and diseases (e.g., gives diseases in text form) dbSAP – single amino-acid polymorphism database for protein variation detection [59] The Human Gene Mutation Database provides gene mutations causing or associated with human inherited diseases and functional SNPs
Genetic markers can be used to study the relationship between an inherited disease and its genetic cause (for example, a particular mutation of a gene that results in a defective protein). It is known that pieces of DNA that lie near each other on a chromosome tend to be inherited together.
In terms of evolution, genetic mutations are the origins of differences in alleles between individuals. However, mutations may also occur within a person's life-time and be passed down from parent to offspring. In some cases, mutations may result in genetic diseases, such as Cystic Fibrosis, which is the result of a mutation to the CFTR gene ...
Frequency-dependent selection may explain the high degree of polymorphism in the MHC. [13] In behavioral ecology, negative frequency-dependent selection often maintains multiple behavioral strategies within a species. A classic example is the Hawk-Dove model of interactions among individuals in a population.