In a given individual, one might find two different versions of this gene at a particular locus.
Genetic engineering[ edit ] In genetic engineeringrecombination can also refer to artificial and deliberate Uses of genetic recombination of disparate pieces of DNA, often from different organisms, creating what is called recombinant DNA.
A prime example of such a use of genetic recombination is gene targetingwhich can be used to add, delete or otherwise change an organism's genes. This technique is important to biomedical researchers as it allows them to study the effects of specific genes.
Techniques based on genetic recombination are also applied in protein engineering to develop new proteins of biological interest. Recombinational repair[ edit ] During both mitosis and meiosis, DNA damages caused by a variety of exogenous agents e. UV lightX-rayschemical cross-linking agents can be repaired by homologous recombinational repair HRR.
In humans and rodents, deficiencies in the gene products necessary for HRR during meiosis cause infertility.
In bacteria, transformation is a process of gene transfer that ordinarily occurs between individual cells of the same bacterial species. Transformation involves integration of donor DNA into the recipient chromosome by recombination.
When two or more viruses, each containing lethal genomic damages, infect the same host cell, the virus genomes can often pair with each other and undergo HRR to produce viable progeny. This process, referred to as multiplicity reactivation, has been studied in lambda and T4 bacteriophages as well as in several pathogenic viruses.
In the case of pathogenic viruses, multiplicity reactivation may be an adaptive benefit to the virus since it allows the repair of DNA damages caused by exposure to the oxidizing environment produced during host infection.
A major incentive for developing a fundamental understanding of the mechanism of meiotic recombination is that such understanding is crucial for solving the problem of the adaptive function of sex, a major unresolved issue in biology. A recent model that reflects current understanding was presented by Anderson and Sekelsky,  and is outlined in the first figure in this article.
The figure shows that two of the four chromatids present early in meiosis prophase I are paired with each other and able to interact. Recombination, in this version of the model, is initiated by a double-strand break or gap shown in the DNA molecule chromatid at the top of the first figure in this article.
However, other types of DNA damage may also initiate recombination. For instance, an inter-strand cross-link caused by exposure to a cross-linking agent such as mitomycin C can be repaired by HRR. As indicated in the first figure, above, two types of recombinant product are produced.
This pathway is labeled in the figure as the DHJ double-Holliday junction pathway.
Thus, explanations for the adaptive function of meiosis that focus exclusively on crossing-over are inadequate to explain the majority of recombination events. Achiasmy and heterochiasmy[ edit ] Achiasmy is the phenomenon where autosomal recombination is completely absent in one sex of a species.
Achiasmatic chromosomal segregation is well documented in male Drosophila melanogaster. Heterochiasmy is the term used to describe recombination rates which differ between the sexes of a species.
In mammals, females most often have higher rates of recombination. The "Haldane-Huxley rule" states that achiasmy usually occurs in the heterogametic sex.Genetic engineering: Genetic engineering, the artificial manipulation, modification, and recombination of DNA or other nucleic acid molecules to modify an organism.
Uses of Genetic Recombination Genetic Recombination Genetic recombination is the method in which a molecule of nucleic acid, usually a strand of DNA (deoxyribonucleic acid) but can possibly be RNA (ribonucleic acid) is broken and then combined with another different strand of nucleic acid.
Recombinant DNA differs from genetic recombination in that the former results from artificial methods in the test tube, while the latter is a normal biological process that results in the remixing of existing DNA sequences in essentially all organisms.
In general recombination (also known as homologous recombination), genetic exchange takes place between a pair of homologous DNA sequences. These are usually located on two copies of the same chromosome, although other types of DNA molecules that share the .
Mar 22, · TRANSCRIPT: A common technique in genetic engineering is to insert a new gene into a loop of bacterial DNA called a plasmid.
The molecular tool . However, the rate of recombination between a specific pair of genetic loci depends on the distance between them and varies from less than 1 percent to approximately 50 percent. Measurement of the recombination frequencies for different loci can be used to map the virus genome.