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Genetic recombination
 
 
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Genetic recombination is the process by which a strand of genetic material (usually DNA
DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetics instructions used in the development and functioning of all known living organisms and some viruses....
; but can also be RNA
RNA

Ribonucleic acid is a type of molecule that consists of a long chain of nucleotide units. Each nucleotide consists of a nucleobase, a ribose sugar, and a phosphate....
) is broken and then joined to a different DNA molecule. In eukaryotes recombination commonly occurs during meiosis
Meiosis

In biology or life science, meiosis is a process of reductional division in which the number of chromosomes per cell is halved. In animals, meiosis always results in the formation of gametes, while in other organisms it can give rise to spores....
 as chromosomal crossover
Chromosomal crossover

Chromosomal crossover is the process by which two chromosomes pair up and exchange sections of their DNA. This often occurs during prophase 1 of meiosis in a process called synapsis....
 between paired chromosomes. This process leads to offspring having different combinations of genes from their parents and can produce new chimeric alleles. In evolutionary biology this shuffling of genes is thought to have many advantages, including that of allowing sexually reproducing organisms to avoid Muller's ratchet
Muller's ratchet

In evolutionary genetics, Muller's ratchet is the process by which the genomes of an Asexual reproduction population accumulate genetic deletion in an irreversible manner....
.

In molecular biology
Molecular biology

Molecular biology is the study of biology at a molecule level. The field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry....
 "recombination" can also refer to artificial and deliberate recombination of disparate pieces of DNA, often from different organisms, creating what is called recombinant DNA
Recombinant DNA

Recombinant DNA is a form of synthetic DNA thereby combining DNA sequences that would not normally occur together. In terms of genetic modification, recombinant DNA is produced through the addition of relevant DNA into an existing organismal genome, such as the plasmid of bacteria, to code for or alter different traits for a specific purpos...
.

Enzyme
Enzyme

Enzymes are biomolecules that catalysis chemical reactions. Almost all enzymes are proteins. In enzymatic reactions, the molecules at the beginning of the process are called Substrate , and the enzyme converts them into different molecules, the products....
s called recombinases
Recombinases

Recombinases are genetic recombination enzymes.Types include:* Cre recombinase* Hin recombinase* RecA/RAD51* Tre recombinase* FLP recombinase...
 catalyze
Catalysis

Catalysis is the process in which the reaction rate of a chemical reaction is either increased or decreased by means of a chemical substance known as a catalyst....
 natural recombination reactions.






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Encyclopedia


Genetic recombination is the process by which a strand of genetic material (usually DNA
DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetics instructions used in the development and functioning of all known living organisms and some viruses....
; but can also be RNA
RNA

Ribonucleic acid is a type of molecule that consists of a long chain of nucleotide units. Each nucleotide consists of a nucleobase, a ribose sugar, and a phosphate....
) is broken and then joined to a different DNA molecule. In eukaryotes recombination commonly occurs during meiosis
Meiosis

In biology or life science, meiosis is a process of reductional division in which the number of chromosomes per cell is halved. In animals, meiosis always results in the formation of gametes, while in other organisms it can give rise to spores....
 as chromosomal crossover
Chromosomal crossover

Chromosomal crossover is the process by which two chromosomes pair up and exchange sections of their DNA. This often occurs during prophase 1 of meiosis in a process called synapsis....
 between paired chromosomes. This process leads to offspring having different combinations of genes from their parents and can produce new chimeric alleles. In evolutionary biology this shuffling of genes is thought to have many advantages, including that of allowing sexually reproducing organisms to avoid Muller's ratchet
Muller's ratchet

In evolutionary genetics, Muller's ratchet is the process by which the genomes of an Asexual reproduction population accumulate genetic deletion in an irreversible manner....
.

In molecular biology
Molecular biology

Molecular biology is the study of biology at a molecule level. The field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry....
 "recombination" can also refer to artificial and deliberate recombination of disparate pieces of DNA, often from different organisms, creating what is called recombinant DNA
Recombinant DNA

Recombinant DNA is a form of synthetic DNA thereby combining DNA sequences that would not normally occur together. In terms of genetic modification, recombinant DNA is produced through the addition of relevant DNA into an existing organismal genome, such as the plasmid of bacteria, to code for or alter different traits for a specific purpos...
.

Enzyme
Enzyme

Enzymes are biomolecules that catalysis chemical reactions. Almost all enzymes are proteins. In enzymatic reactions, the molecules at the beginning of the process are called Substrate , and the enzyme converts them into different molecules, the products....
s called recombinases
Recombinases

Recombinases are genetic recombination enzymes.Types include:* Cre recombinase* Hin recombinase* RecA/RAD51* Tre recombinase* FLP recombinase...
 catalyze
Catalysis

Catalysis is the process in which the reaction rate of a chemical reaction is either increased or decreased by means of a chemical substance known as a catalyst....
 natural recombination reactions. RecA
RecA

RecA is a 38 Dalton Escherichia coli protein essential for the repair and maintenance of DNA. RecA has a structural and functional homolog in every species in which it has been seriously sought and serves as an archetype for this class of homologous DNA repair proteins....
, the recombinase found in E. coli
Escherichia coli

'Escherichia coli' , is a Gram negative bacterium that is commonly found in the lower gastrointestinal tract of warm-blooded animals. Most E....
, is responsible for the repair of DNA double strand breaks (DSBs). In yeast and other eukaryotic
Eukaryote

Animals, plants, fungus, and protists are eukaryotes , organisms whose Cell are organized into complex structures enclosed within Cell membrane....
 organisms there are two recombinases required for repairing DSBs. The RAD51
RAD51

RAD51 is a human gene. The protein encoded by this gene is a member of the RAD51 protein family which assist in repair of DNA_repair#Double-strand_breaks....
 protein is required for mitotic
Mitosis

Mitosis is the process in which a eukaryotic cell separates the chromosomes in its cell nucleus, into two identical sets in two daughter nuclei....
 and meiotic
Meiosis

In biology or life science, meiosis is a process of reductional division in which the number of chromosomes per cell is halved. In animals, meiosis always results in the formation of gametes, while in other organisms it can give rise to spores....
 recombination and the DMC1 protein is specific to meiotic recombination.

Chromosomal crossover

Morgan Crossover 1
Chromosomal crossover refers to recombination between the paired chromosome
Chromosome

A chromosome is an organized structure of DNA and protein that is found in Cell . A chromosome is a single piece of DNA that contains many genes, regulatory sequence and other genetic sequence....
s inherited from each of one's parents, generally occurring during meiosis
Meiosis

In biology or life science, meiosis is a process of reductional division in which the number of chromosomes per cell is halved. In animals, meiosis always results in the formation of gametes, while in other organisms it can give rise to spores....
. During prophase I
Meiosis

In biology or life science, meiosis is a process of reductional division in which the number of chromosomes per cell is halved. In animals, meiosis always results in the formation of gametes, while in other organisms it can give rise to spores....
 the four available chromatid
Chromatid

A chromatid is one among the two identical copies of DNA making up a replicated chromosome, which are joined at their centromeres, for the process of cell division ....
s are in tight formation with one another. While in this formation, homologous
Homology (biology)

In evolutionary biology, homology refers to any similarity between characteristics that is due to their common descent. The word homologous derives from the ancient Greek ??????e??, 'to agree'....
 sites on two chromatids can mesh with one another, and may exchange genetic information.

Because recombination can occur with small probability at any location along chromosome, the frequency of recombination between two locations depends on their distance. Therefore, for genes sufficiently distant on the same chromosome the amount of crossover is high enough to destroy the correlation between alleles.

Gene Conversion

In gene conversion, a section of genetic material is copied from one chromosome to another, but leaves the donating chromosome unchanged.

Nonhomologous recombination


Recombination can occur between DNA sequences that contain no sequence homology
Homology (biology)

In evolutionary biology, homology refers to any similarity between characteristics that is due to their common descent. The word homologous derives from the ancient Greek ??????e??, 'to agree'....
. This is referred to as Nonhomologous recombination or nonhomologous end joining
Non-homologous end joining

Non-homologous end joining is a pathway that repairs double-strand breaks in DNA. NHEJ is referred to as "non-homologous" because the break ends are directly ligated without the need for a homologous template, in contrast to homologous recombination, which requires a homologous sequence to guide repair....
.

In B cells

B cells of the immune system
Immune system

An immune system is a collection of biological processes within an organism that protects against disease by identifying and killing pathogens and tumour cells....
 perform genetic recombination, called immunoglobulin class switching. It is a biological mechanism that changes an antibody from one class to another, for example, from an isotype called IgM to an isotype called IgG.

See also

  • Recombination frequency
  • Recombination hotspot
    Recombination hotspot

    Recombination hotspots are small regions in the genome of sexually reproducing organisms that exhibit highly elevated rates of meiotic Genetic recombination....
  • Four Gamete Test
    Four Gamete Test

    In population genetics, the Four Gamete Test is a method for detecting historical Genetic recombination events ....
  • Somatic recombination


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