Heteroduplex
Encyclopedia
A heteroduplex is a double-stranded (duplex
Duplex
Duplex commonly means double or twofold.It may also refer to:* Duplex , a two-unit apartment building or condominium* Duplex, a common electrical receptacle with two NEMA type 5 plugs* Duplex locomotive, a type of steam locomotive...

) molecule of nucleic acid
Nucleic acid
Nucleic acids are biological molecules essential for life, and include DNA and RNA . Together with proteins, nucleic acids make up the most important macromolecules; each is found in abundance in all living things, where they function in encoding, transmitting and expressing genetic information...

 originated through the genetic recombination
Genetic recombination
Genetic recombination is a process by which a molecule of nucleic acid is broken and then joined to a different one. Recombination can occur between similar molecules of DNA, as in homologous recombination, or dissimilar molecules, as in non-homologous end joining. Recombination is a common method...

 of single complementary strands derived from different sources, such as from different homologous chromosomes or even from different organisms.
One such example is the heteroduplex DNA strand formed in hybridization processes, usually for biochemistry
Biochemistry
Biochemistry, sometimes called biological chemistry, is the study of chemical processes in living organisms, including, but not limited to, living matter. Biochemistry governs all living organisms and living processes...

-based phylogenetical analyses. Another example is the heteroduplexes formed when non-natural analogs of nucleic acids are used to bind with nucleic acids; these heteroduplexes result from performing antisense techniques using single-stranded peptide nucleic acid, 2'-O-methyl phosphorothioate or Morpholino
Morpholino
In molecular biology, a Morpholino is a molecule in a particular structural family that is used to modify gene expression. Morpholino oligomers are an antisense technology used to block access of other molecules to specific sequences within nucleic acid...

 oligos to bind with RNA.

In meiosis, the process of crossing-over occurs between non-sister chromatids, which results in new allelic combinations of a population. In crossing-over, a Spo11
SPO11
Spo11 is a protein used in a complex along with Mre11 and Rad50 during meiotic recombination. It is also involved in the creation of double stranded breaks in the DNA in the early stages of this process. Its active site contains a tyrosine which ligates and dissociates with DNA to promote break...

enzyme makes staggered nicks in a pair of sister chromatid strands (in a tetrad organization of prophase). The enzyme trims back the 5' ends of the strand and a protein complex binds to the 3' single-stranded ends. Rad51 protein is recruited and binds in a protein complex to search for a complementary sequence analogous to double-strand-break repair. The filament searches for the homologous chromosome, strand invasion occurs where the new chromosome forms a D-loop over the bottom sister chromatid, then the ends are annealed. This process can yield double Holliday Junctions that when cut in a transversal pattern by endonucleases form 2 heteroduplex strand products.

Heteroduplex DNA is also a source of small RNAs (smRNAs), causing post-transcriptional gene silencing.
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