DNA recombination

Definition

Target type: biologicalprocess

Any process in which a new genotype is formed by reassortment of genes resulting in gene combinations different from those that were present in the parents. In eukaryotes genetic recombination can occur by chromosome assortment, intrachromosomal recombination, or nonreciprocal interchromosomal recombination. Interchromosomal recombination occurs by crossing over. In bacteria it may occur by genetic transformation, conjugation, transduction, or F-duction. [ISBN:0198506732]

DNA recombination is a fundamental biological process that involves the exchange of genetic material between two DNA molecules. This process is essential for the diversity and evolution of life, playing a crucial role in various cellular functions, including repair of DNA damage, generation of genetic diversity during meiosis, and the integration of foreign DNA into the host genome. There are two primary types of DNA recombination: homologous recombination and non-homologous recombination.

Homologous recombination occurs between DNA sequences that share significant similarity. This process is initiated by a double-strand break (DSB) in one DNA molecule. The broken ends are then processed by enzymes, creating 3’ single-stranded overhangs. These overhangs invade the homologous DNA molecule, searching for complementary sequences. Once a match is found, the invaded strand is used as a template for DNA synthesis, resulting in the formation of a Holliday junction. This structure is a point where the two DNA molecules are intertwined, allowing for the exchange of genetic information. The Holliday junction can then be resolved by enzymes, resulting in the formation of two recombinant DNA molecules.

Non-homologous recombination, on the other hand, involves the exchange of genetic material between DNA sequences that do not share significant similarity. This process is typically mediated by enzymes called transposases, which can move DNA segments from one location to another within the genome. Non-homologous recombination often results in the creation of new genes or the disruption of existing genes, leading to significant changes in the organism’s genetic makeup.

In the context of DNA repair, homologous recombination plays a vital role in repairing DSBs, which can be caused by various factors, such as ionizing radiation or chemical mutagens. By using the homologous chromosome as a template, homologous recombination ensures that the broken DNA sequence is accurately repaired, minimizing the risk of mutations.

During meiosis, homologous recombination is essential for generating genetic diversity. During prophase I, homologous chromosomes pair up and exchange genetic information through a process called crossing over. This process results in the shuffling of alleles between homologous chromosomes, producing daughter cells with unique combinations of genes. This diversity is critical for the survival and evolution of species, allowing them to adapt to changing environments.

Furthermore, homologous recombination plays a crucial role in the integration of foreign DNA into the host genome. This process is essential for the successful integration of viral DNA into the host genome during viral infection. Additionally, homologous recombination can be used to introduce new genes into organisms, allowing for the creation of genetically modified organisms with specific traits.

In conclusion, DNA recombination is a complex and fundamental biological process that is essential for various cellular functions. It plays a vital role in DNA repair, genetic diversity, and the integration of foreign DNA into the host genome. This process is crucial for the evolution and survival of all living organisms.'
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Proteins (10)

Compounds (52)