Gene recombination is the exchange of genetic material between different organisms. It results in the production of offspring with combinations of traits that differ from those found in both parents. Most of these genetic exchanges occur naturally.
How it happens
Gene recombination begins as a result of the separation of genes during the formation of gametes during meiosis, fertilization and crossing. Crossing allows alleles on DNA molecules to change position from one homologous chromosome segment to another. Recombination is responsible for the genetic diversity of a species or population.
Chromosome structure
Chromosomes are located inside the nucleus of cells. They are formed from chromatin, a mass of genetic material made of DNA that is wrapped tightly around proteins called histones. The chromosome is usually single stranded and consists of a centromere region that connects the long and short regions.
Duplication of chromosomes
When a cell enters its life cycle, its chromosomesare duplicated through DNA replication in preparation for division. Each duplicated chromosome consists of two identical ones, called sister chromatids. They are associated with the centromere region. When cells divide, paired sets are formed. They consist of one chromosome (homologous) from each parent.
Chromosomal exchange
Gene recombination during crossing over was first described by Thomas Hunt Morgan. In eukaryotes, it is facilitated by chromosome crossing. The process of crossing results in the offspring having different combinations of genes and can produce new chimeric alleles. This allows sexually reproducing organisms to avoid Moeller's ratchet, in which the genomes of an asexual population accumulate genetic deletions in an irreversible manner.
During prophase I, the four chromatids are tightly connected. In this formation, homologous sites on two molecules can closely pair with each other and exchange genetic information. Gene recombination can occur anywhere along the chromosome. Its frequency between two points depends on the distance separating them.
Meaning
Tracking the movement of genes as a result of crossovers has proven to be very useful for geneticists. This makes it possible to determine how far apart two genes are on a chromosome. Science can also use this method to infer the presence of certain genes. One molecule in a bonded pair serves as a marker to detect the presence of the other. It is used to detect the presence of pathogensgenes.
The frequency of recombination between two observed loci is the intersection value. It depends on the mutual distance of the observed genetic foci. For any fixed set of environmental conditions, recombination in a particular region of the bond structure (the chromosome) tends to be constant. The same is true for the intersection value, which is used when generating genetic maps.
Meiosis
Chromosomal crossover involves the exchange of paired chromosomes inherited from each parent. Meiosis, as the basis of gene recombination, plays an important role in this process. Molecular models of this process have evolved over the years as evidence has accumulated. The new model demonstrates that two of the four chromatids present at the beginning of meiosis (prophase I) are paired with each other and are able to interact. Recombination of chromosomes and genes takes place in it. However, explanations of the adaptive function of meiosis that focus solely on intersection are insufficient for most exchange events.
Mitosis and non-homologous chromosomes
In eukaryotic cells, crossover can also occur during mitosis. This results in two cells with identical genetic material. Any crossover that occurs between homologous chromosomes in mitosis does not produce a new combination of genes.
The crossing that occurs in non-homologous chromosomes can produce a mutation known astranslocation. It occurs when a segment of a chromosome separates from and moves to a new position on a non-homologous molecule. This type of mutation can be dangerous, as it often leads to the development of cancerous cells.
Gene Conversion
When genes are transformed, part of the genetic material is copied from one chromosome to another without changing the donor. Gene conversion occurs at a high frequency in the actual location. This is the process by which a DNA sequence is copied from one helix to another. Recombination of genes and chromosomes has been studied in fungal crosses, where it is convenient to observe the four products of individual meioses. Gene conversion events can be distinguished as deviations in individual cell division from normal 2:2 segregation.
Gene engineering
Gene recombination can be artificial and deliberate. It is used on disparate DNA fragments, often from different organisms. Thus, recombinant DNA is obtained. Artificial recombination can be used to add, remove, or change an organism's genes. This method is important for biomedical research in the field of genetic and protein engineering.
Recombinant recovery
During mitosis and meiosis, DNA damaged by various exogenous factors can be saved by the homologous repair step (HRS). In humans and rodents, a deficiency in the gene products required for FGF during meiosis causes infertility.
Bacteriatransformation is the process of gene transfer that usually occurs between individual cells of the same species. It involves the integration of donor DNA into the recipient's chromosome through gene recombination. This process is an adaptation to repair damaged cells. Transformation may benefit pathogenic bacteria by allowing repair of DNA damage that occurs in the inflammatory, oxidative environment associated with host infection.
When two or more viruses, each containing lethal genomic damage, infect the same host cell, the genomes can mate with each other and pass through the FGP to produce viable offspring. This process is called multiplicity reactivation. It has been studied in several pathogenic viruses.
Recombination in prokaryotic cells
Prokaryotic cells, like single-celled bacteria without a nucleus, also undergo genetic recombination. In this case, the genes of one bacterium are included in the genome of another by crossing. Bacterial recombination is carried out by the processes of conjugation, transformation or transduction.
In conjugation, one bacterium is connected to another through a protein tubular structure. In the process of transformation, prokaryotes take DNA from the environment. They most often come from dead cells.
In transduction, DNA is exchanged through a virus that infects bacteria, known as a bacteriophage. Once the foreign cell is internalized through conjugation, transformation, or transduction,the bacterium can insert its segments into its own DNA. This transfer is carried out by crossing and leads to the creation of a recombinant bacterial cell.
