Synapsis

Synapsis

Synapsis (also called syndesis) is the pairing of two homologous chromosomes that occurs during meiosis. [cite journal |author=McKee B |title=Homologous pairing and chromosome dynamics in meiosis and mitosis |journal=Biochim Biophys Acta |volume=1677 |issue=1-3 |pages=165–80 |year=2004 |pmid=15020057] It is a form of chromosomal crossover. Synapsis takes place during prophase I. When homologous chromosomes synapse, they come closer together until they are connected by a protein complex called the synaptonemal complex, which contains central and lateral elements. [cite journal |author=Revenkova E, Jessberger R |title=Shaping meiotic prophase chromosomes: cohesins and synaptonemal complex proteins |url=http://www.springerlink.com/content/fm26j18850w2762t/fulltext.pdf |journal=Chromosoma |volume=115 |issue=3 |pages=235–40 |year=2006 |pmid=16518630 |doi=10.1007/s00412-006-0060-x] While autosomes undergo synapsis during meiosis sex chromosomes usually remain unpaired. [cite journal |author=Page J, de la Fuente R, Gómez R, Calvente A, Viera A, Parra M, Santos J, Berríos S, Fernández-Donoso R, Suja J, Rufas J |title=Sex chromosomes, synapsis, and cohesins: a complex affair |url=http://www.springerlink.com/content/1683677374l40532/fulltext.pdf |journal=Chromosoma |volume=115 |issue=3 |pages=250–9 |year=2006 |pmid=16544151 |doi=10.1007/s00412-006-0059-3]

When the non-sister chromatids intertwine, segments of chromatids with the same sequence break apart at and are exchanged in a process known as genetic recombination or "crossing-over". Recombination exchanges genetic material between homologous chromosomes and increases the genetic variability of the offspring. This exchange produces a chiasma, a region that is shaped like an X, where the two chromosomes are physically joined.

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Look at other dictionaries:

  • synapsis — ● synapsis nom féminin Synonyme de stade zygotène. ● synapsis (synonymes) nom féminin Synonymes : stade zygotène …   Encyclopédie Universelle

  • synapsis — pl. synapses, 1895 in biology, Mod.L., from Gk. synapsis “connection, junction” (see SYNAPSE (Cf. synapse)) …   Etymology dictionary

  • synapsis — synapsis. См. синапсис. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • synapsis — synapsis. = chromosome pairing (см.). (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • synapsis — [si nap′sis] n. pl. synapses [si nap′sēz΄] [ModL < Gr, junction, connection < syn , together + apsis, a joining < haptein, to join] 1. Genetics the association side by side of homologous maternal and paternal paired chromosomes in the… …   English World dictionary

  • Synapsis — La synapsis ou appariement est l union des chromosomes homologues qui donnent des tétrades , des groupes de 4 chromatides . La synapsis se déroule grâce à la formation du complexe synaptonémal, composé d une longue matrice protéique de chaque… …   Wikipédia en Français

  • Synapsis — ◆ Syn|ạp|sis 〈f.; ; unz.; Biol.〉 während der ersten Phase der Reduktionsteilung sich vollziehende Paarung der sich entsprechenden Chromosomen [<Syn... + grch. hapsis „Verbindung, Führung, Rundung, Wölbung“] ◆ Die Buchstabenfolge syn|a... bzw …   Universal-Lexikon

  • Synapsis — Meiose am Beispiel der Spermatogenese Unter Meiose (von griech.: meiono = vermindern, verkleinern), Reifeteilung oder Reduktionsteilung versteht man eine besondere Form der Zellkernteilung, wobei im Unterschied zur gewöhnlichen Kernteilung, der… …   Deutsch Wikipedia

  • synapsis — n.; pl. ses [Gr. synapsis, union] The intimate conjunction of homologous chromosomes that occurs during the prophase of the meiotic division …   Dictionary of invertebrate zoology

  • synapsis — synaptic /si nap tik/, synaptical, adj. synaptically, adv. /si nap sis/, n., pl. synapses / seez/. 1. Also called syndesis. Cell Biol. the pairing of homologous chromosomes, one from each parent, during early meiosis. 2. Physiol. synapse. [1645… …   Universalium

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