DNA recombination essentially refers to genetic recombination, also known as genetic shuffling, which refers to the exchange of genetic material between two different sister chromosomes.DNA recombination leads to the generation of new traits different from any parent.DNA recombination during meiosis in eukaryotes produces new genetic information, which can be passed from parents to offspring.
DNA recombination essentially refers to genetic recombination, also known as genetic shuffling, which refers to the exchange of genetic material between two different sister chromosomes.DNA recombination leads to the generation of new traits different from any parent.DNA recombination during meiosis in eukaryotes produces new genetic information, which can be passed from parents to offspring.Most DNA recombination occurs naturally.
DNA recombination in eukaryotic meiosis involvesHomologous chromosomeThe pairing of chromosomes and the subsequent exchange of information between chromosomes.Information exchange can be completed through replication, as well as DNA strand breakage and repair.In meiosis and mitosis, recombination occurs in similarDNA molecule(homologous sequence).During meiosis, non sister homologous chromosomes pair with each other, resulting in DNA recombination between non sister homologues.In meiotic and mitotic cells, recombination between homologous chromosomes is a common mechanism for DNA repair.
Gene transformation, the process of homologous sequence replication, also belongs to DNA recombination.
It can artificially induce DNA recombination in the laboratory (in vitro) environment to produce recombinant DNA for vaccine development.
mechanism
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Genetic recombinationCatalyzed by many different enzymes.Recombinase is a key enzyme that catalyzes the chain transfer step in the process of DNA recombination.RecA is mainly found in Escherichia coliRecombinase, responsible for repairing DNA double strand breaks (DSBs).In yeast and other eukaryotes, the repair of DSB requires two recombinant enzymes.RAD51 protein is necessary for mitotic and meiotic recombination, and DNA repair protein DMC1 is specific for meiotic recombination.In archaea, bacteriaRecA proteinThe ortholog of is RadA.
Chromosome exchange
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Chromosome exchange in eukaryotes promotes DNA recombination during meiosis.The exchange process results in offspring having different gene combinations from their parents, and occasionally new chimeric alleles can be generated.Gene rearrangement caused by DNA recombination increases genetic variation.
Chromosome crossing involves recombination between paired chromosomes inherited from parents, usually inMeiosisOccurs in the process.During the early I (thick line period), fourChromatidThe homologous sites on two paired chromatids can closely pair with each other and exchange genetic information[1]。Because recombination can occur at any position of the chromosome with a small probability, the recombination frequency between two loci depends on the distance between them.Therefore, for genes far enough away on the same chromosome, the amount of exchange is enough to destroy the correlation between alleles.
Gene transformation
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stayGene transformationIn, part of the genetic material on one chromosome is copied to another chromosome, while the sequence of the chromosome providing this part of genetic material has not been changed.stayMeiosisDNA recombination sites and gene transformation occur frequently.Gene transformation is usually studied in fungal hybridization[2]Among them, four products of single meiosis can be conveniently observed.
genetic engineeringDNA recombination in refers to the artificial recombination of DNA fragments from different organisms to produce the so-calledRecombinant DNA。Genetic engineering can be used to add, delete or otherwise change the genes of organisms, mainly for biomedical research, to study the function of specific genes.Genetic engineering is also widely used inTransgenic organismespeciallyTransgenic plantandTransgenic animalAnd the cultivation of new varieties of transgenic microorganisms.The technology based on genetic engineering is also applied toProtein EngineeringTo develop new proteins with biological significance.
Recombination repair
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DNA damage caused by various exogenous factors (such as ultraviolet ray, X-ray, chemical cross-linking agent) during mitosis and meiosis can be repaired by homologous recombination repair mechanism (HRR)[4]。
Defects in gene products necessary for HRR during meiosis in humans and rodents can lead to infertility[4]。Defects in gene products necessary for human HRR (such as BRCA1 and BRCA2) will also increase the risk of cancer.In bacteria, transformation is the process of introducing foreign genes.Transformation involves the integration of donor DNA into recipient chromosomes through recombination, which is also completed through HRR repair[5]。
When two or more viruses (each containing fatal genomic damage) infect the samehost cellWhen,Viral genomeUsually they can pair with each other and experience HRR to produce normal offspring.This process is called multiple reactivation.
Meiotic recombination
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Two of the four chromatids (prophase I) that appear at the early stage of meiosis pair with each other and can interact with each other.The recombination was caused by double strand breakage.Other types of DNA damage may also trigger recombination.For example, crosslinking agents such asMitomycin CThe cross-linking between chains can be repaired by HRR, which can lead to recombination.
There are two kinds of recombinant products: the "crossover" (CO) type whose flanking regions are exchanged and the "non crossover" (NCO) type whose flanking regions are not exchanged.CO type recombination forms two "Holliday junctions" through the DHJ pathway, and there is a single chain exchange between the two participating chromatids in each junction.NCO recombinants are produced by a method called synthesis dependent chain annealing (SDSA).NCO/SDSA type restructuring events seem to be more common than CO/DHJ type[4]。
