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Gene duplications can arise as products of several types of errors in DNA replication and repair machinery as well as through fortuitous capture by selfish genetic elements. Common sources of gene duplications include ectopic recombination , retrotransposition event, aneuploidy , polyploidy , and replication slippage .
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 study of human genetic variation has evolutionary significance and medical applications. It can help scientists reconstruct and understand patterns of past human migration. In medicine, study of human genetic variation may be important because some disease-causing alleles occur more often in certain population groups.
Copy number variation was initially thought to occupy an extremely small and negligible portion of the genome through cytogenetic observations. [12] Copy number variations were generally associated only with small tandem repeats or specific genetic disorders, [13] therefore, copy number variations were initially only examined in terms of specific loci.
RNA-dependent RNA polymerase (RdRp) or RNA replicase is an enzyme that catalyzes the replication of RNA from an RNA template. Specifically, it catalyzes synthesis of the RNA strand complementary to a given RNA template.
Crossing over occurs between prophase I and metaphase I and is the process where two homologous non-sister chromatids pair up with each other and exchange different segments of genetic material to form two recombinant chromosome sister chromatids. It can also happen during mitotic division, [1] which may result in loss of heterozygosity.
The smallest single base deletion mutations occur by a single base flipping in the template DNA, followed by template DNA strand slippage, within the DNA polymerase active site. [ 3 ] [ 4 ] [ 5 ] Deletions can be caused by errors in chromosomal crossover during meiosis , which causes several serious genetic diseases .
Probes not binding to the intended sequence do not achieve sufficient localized fluorescence to be distinguished from background. [ 18 ] Single-molecule RNA FISH assays can be performed in simplex or multiplex , and can be used as a follow-up experiment to quantitative PCR , or imaged simultaneously with a fluorescent antibody assay.