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Gene duplication. Gene duplication (or chromosomal duplication or gene amplification) is a major mechanism through which new genetic material is generated during molecular evolution. It can be defined as any duplication of a region of DNA that contains a gene. Gene duplications can arise as products of several types of errors in DNA replication ...
Evolution by gene duplication is an event by which a gene or part of a gene can have two identical copies that can not be distinguished from each other. This phenomenon is understood to be an important source of novelty in evolution, providing for an expanded repertoire of molecular activities. The underlying mutational event of duplication may ...
Mutations can involve the duplication of large sections of DNA, usually through genetic recombination. [10] These duplications are a major source of raw material for evolving new genes, with tens to hundreds of genes duplicated in animal genomes every million years. [11] Most genes belong to larger gene families of shared ancestry, detectable ...
Copy number variation is a type of structural variation: specifically, it is a type of duplication or deletion event that affects a considerable number of base pairs. [2] Approximately two-thirds of the entire human genome may be composed of repeats [3] and 4.8–9.5% of the human genome can be classified as copy number variations. [4]
2R hypothesis. The 2R hypothesis or Ohno's hypothesis, first proposed by Susumu Ohno in 1970, [1] is a hypothesis that the genomes of the early vertebrate lineage underwent two whole genome duplications, and thus modern vertebrate genomes reflect paleopolyploidy. The name derives from the 2 rounds of duplication originally hypothesized by Ohno ...
Unequal crossing over. Unequal crossing over is a type of gene duplication or deletion event that deletes a sequence in one strand and replaces it with a duplication from its sister chromatid in mitosis or from its homologous chromosome during meiosis. It is a type of chromosomal crossover between homologous sequences that are not paired precisely.
Neofunctionalization is the process by which a gene acquires a new function after a gene duplication event. The figure shows that once a gene duplication event has occurred one gene copy retains the original ancestral function (represented by the green paralog), while the other acquires mutations that allow it to diverge and develop a new function (represented by the blue paralog).
The most frequent reported symptoms in patients with 22q11.2 duplication syndrome are intellectual disability /learning disability (97% of patients), delayed psychomotor development (67% of patients), growth retardation (63% of patients) and muscular hypotonia (43% of patients). [1] However, these are common and relatively non-specific ...