In essence, DNA recombination refers to gene recombination, also known as genetic rearrangement, which refers to the exchange of genetic material between two different sister chromosomes. DNA recombination will bring new characteristics to future generations that are different from those of any parents. 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 meiosis of eukaryotes involves the pairing of homologous chromosomes and the subsequent information exchange between chromosomes. Information exchange can be accomplished by replication, or by breaking and repairing DNA chains. In meiosis and mitosis, similar DNA molecules (homologous sequences) recombine. In meiosis, non-sister homologous chromosomes pair with each other, which leads to DNA recombination between non-sister homologous chromosomes. In meiotic splinter cell and mitotic cells, recombination between homologous chromosomes is a common mechanism of DNA repair.
Gene transformation-the process of copying homologous sequences, also belongs to DNA recombination.
DNA recombination and the repair of recombinant DNA also occur in asexual bacteria and archaea.
DNA recombination can be induced artificially in laboratory (in vitro) environment to produce recombinant DNA for vaccine development.
Chromosome exchange
Chromosome exchange in eukaryotes promotes DNA recombination during meiosis. The exchange process leads to offspring with different gene combinations from their parents, and occasionally new chimeric alleles are produced. Gene rearrangement caused by DNA recombination increases genetic variation.
Chromosome crossing involves recombination between pairs of chromosomes inherited from parents, which usually occurs during meiosis. In prophase I (pachytene), four chromatids are closely clustered with each other, and homologous sites on two pairs of chromatids can be closely paired with each other, and genetic information can be exchanged. Because recombination can occur anywhere on the chromosome, the probability is small, so the recombination frequency between two loci depends on the distance between them. Therefore, for genes far enough away on the same chromosome, the exchange ability is enough to destroy the correlation between alleles.
Meselson Latin
In gene transformation, part of the genetic material on one chromosome is copied to another chromosome, but the chromosome sequence providing this part of the genetic material has not changed. At the site of meiotic DNA recombination, gene transformation occurs with high frequency. Fungal hybridization usually studies gene transformation? Among them, four products of single meiosis can be observed conveniently.
nonhomologous recombination
In gene transformation, part of the genetic material on one chromosome is copied to another chromosome, but the chromosome sequence providing this part of the genetic material has not changed. At the site of meiotic DNA recombination, gene transformation occurs with high frequency. Fungal hybridization usually studies gene transformation? Among them, four products of single meiosis can be observed conveniently.
Meiosis recombination
Two of the four chromatids in prophase of meiosis (prophase I) are paired and can interact with each other. Double strand breaks initiate recombination. Other types of DNA damage may also trigger recombination. For example, interchain cross-linking caused by cross-linking agent such as mitomycin C can be repaired by HRR to start recombination.
There are two kinds of recombinant products: the "hybrid" (CO) type in which the flanking regions of chromosomes are exchanged and the "non-hybrid" (NCO) type in which the flanking regions of chromosomes are not exchanged. Homotypic recombination forms two "Holiday junctions" through DHJ pathway, and there is single-strand exchange between the two participating chromatids in each junction. NCO recombinants are produced by a method called "Synthetic Dependent Chain Annealing" (SDSA). Reorganization events of NCO/SDSA type seem to be more common than those of CO/DHJ type.