Phenomena and Processes

Genetic Crossing Over

The reciprocal exchange of segments at corresponding positions along pairs of homologous CHROMOSOMES by symmetrical breakage and crosswise rejoining forming cross-over sites (HOLLIDAY JUNCTIONS) that are resolved during CHROMOSOME SEGREGATION. Crossing-over typically occurs during MEIOSIS but it may also occur in the absence of meiosis, for example, with bacterial chromosomes, organelle chromosomes, or somatic cell nuclear chromosomes.

National Library of MedicineMedical Subject Headings2026

Structured Summary

Abstract

The reciprocal exchange of segments at corresponding positions along pairs of homologous CHROMOSOMES by symmetrical breakage and crosswise rejoining forming cross-over sites (HOLLIDAY JUNCTIONS) that are resolved during CHROMOSOME SEGREGATION. Crossing-over typically occurs during MEIOSIS but it may also occur in the absence of meiosis, for example, with bacterial chromosomes, organelle chromosomes, or somatic cell nuclear chromosomes.

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Synonyms

5 entry terms
  • Crossing Over
  • Crossing Over, Genetic
  • Crossing-Over, Genetic
  • Crossing Overs
  • Genetic Crossing-Over

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Aspects Covered

6 allowable subheadings

Indexed with the subheadings drug effects, ethics, genetics, immunology, physiology, radiation effects.

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Indexing Annotation

do not confuse with CROSSES, GENETIC, the result of breeding 2 varieties of the same species

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History Note

2005(1968)

MeSH Record

Previous Indexing

  • Cytogenetics (1967)
  • Genetics (1966-1967)

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References

  1. National Library of Medicine. Genetic Crossing Over. Medical Subject Headings (MeSH). 2026. Unique ID D003434. http://id.nlm.nih.gov/mesh/2026/D003434
  2. Genetic Crossing Over. In: Wikipedia. https://en.wikipedia.org/wiki/Chromosomal_crossover
  3. Genetic Crossing Over. In: Wikidata. https://www.wikidata.org/wiki/Q244145