bivalent

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Related to bivalents: bivalent chromosome

bivalent

 [bi-va´lent]
the structure formed by a pair of homologous chromosomes joined by synapsis along their length during the zygotene and pachytene stages of the first meiotic prophase. After each homologous chromosome splits into two sister chromatids during the pachytene stage, this structure is called a tetrad.

bi·va·lent

(bī-vā'lent, biv'ă-lent),
1. Having a combining power (valence) of 2.
See also: tetrad. Synonym(s): divalent
2. In cytology, a structure consisting of two paired homologous chromosomes, each split into two sister chromatids, as seen during the pachytene stage of prophase in meiosis.
See also: tetrad.

bivalent

/bi·va·lent/ (bi-va´lent)
2. the structure formed by a pair of homologous chromosomes by synapsis along their length during the zygotene and pachytene stages of the first meiotic prophase.

bivalent

(bī-vā′lənt)
adj.
1. Genetics Relating to or being a pair of homologous, side-by-side chromosomes, especially during meiosis; double.
2. Chemistry & Immunology Divalent.

bi·va′lence, bi·va′len·cy n.

bivalent

[bīvā′lənt]
Etymology: L, bis + valere, to be powerful
1 See divalent. (in genetics) a pair of synapsed homologous chromosomes that are attached to each other by chiasmata during the early first meiotic prophase of gametogenesis. The structure serves as the basis for the tetrads from which gametes are produced during the two meiotic divisions.
2 See valence, def. 1. bivalence, n.

bivalent

Chemistry
adjective Referring to an atom with 2 valent states.
 
Genetics
adjective Referring to either of 2 homologous chromosomes in synapsis during meiosis.

bi·va·lent

(bī-vā'lĕnt)
1. Having a combining power (valence) of two.
Synonym(s): divalent.
2. cytology a structure consisting of two paired homologous chromosomes, each split into two sister chromatids, as seen during the pachytene stage of prophase in meiosis.

bivalent

(of a pair of homologous CHROMOSOMES) being paired during prophase I of MEIOSIS. Compare MULTIVALENT.

bivalent

1. having a valence of two.
2. denoting homologous chromosomes associated in pairs during the first meiotic prophase.
References in periodicals archive ?
At earlier stages of meiosis, both normal plants and Ph mutants show multivalent formation, but correction of multivalents into bivalents takes place only in the former.
amp; Gray, that shows tetrasomic inheritance, yet at MI forms only bivalents (Soltis & Rieseberg, 1986).
Whereas the chromosomes of the TMM hybrids paired mostly as M-M bivalents, leaving the T chromosomes as univalents, pairing in the TTM hybrids led predominantly to the formation of trivalents.
hybrids, B-chromosomes reduce the number of multivalents, restricting chromosome pairing to form bivalents (Evan & Macefield, 1973; Taylor & Evans, 1977).
Chapman and Kimber (1992a) note that autotetraploids that form an excess of bivalents at metaphase I violate this assumption, but might form an exception - the question being whether the formation of excess bivalents is due to interference or due to preferential pairing caused by "cryptic differences among homologues" (p.
Silicas and Gerstel (1962) reported minor but significant differences in the number of bivalents between fixations made on different days of some Nicotiana hybrids, and similarly Menzel and Wilson (1966) observed changes in the pattern of chromosome pairing in a Hibiscus hybrid.
typhoides (2n = 14) and P purpureum (2n = 28), but Jauhar (1968) showed that a large number of the bivalents observed in the hybrid was actually formed between the two sets of chromosomes of P.