bivalent


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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

(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

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.
References in periodicals archive ?
Both vaccines are currently in use in Bulgaria; the quadrivalent one was introduced in 2007, and the bivalent one in 2008.
In diplotene/diakinesis some the autosomal bivalents shows telomeric associations (Fig.
The infants received either the monovalent, bivalent or trivalent vaccines in two doses - once at birth, the other after 30 days.
Among the species used for this purpose, a special interest in the cytogenetics of the genus Stethophyma (previously named Mecostethus) arose from three main fascinating characteristics: i) the tendency for chiasmata to occur close to the centomeric regions in most bivalents (Darlington 1932; White 1936; Shaw 1970, 1971a; Jones 1971, 1973); ii) occurrence of ditactic bivalents (McClung 1928; White 1951, 1973; Shaw 1970, 1971a); iii) extended polymorphisms with respect to supernumerary heterochromatic segments, in addition to a marked interpopulation variation for standard heterochromatin in a number of autosomes (McClung 1928; Carothers 1931; Shaw 1970, 1971a; Jones 1971; Santos unpub.
We calculated the mean chiasma frequency as 1.03 per bivalent. More specifically, we observed two bivalents with two chiasmata in five diplotene nuclei and one bivalent with three chiasmata in five diplotene nuclei.
In the studied accessions from Pterocaulon polystachyum (Table 1), the following were observed: 9 bivalent chromosomes (II) in diakinesis and metaphase 1 (Figure 1e, 1f), and normal chromosomal segregation in anaphase and telophase I and II (9-9), even though some irregularities occurred, like a telophasic bridge (Figure 1g) and a retarding chromosome in one cell.
Using individual monomeric Anticalins selected to have picomolar binding affinity to distinct determinants on two defined clinically validated targets, Pieris has constructed Duocalins as monomeric, bivalent binding proteins that retain target specificity and affinity regardless of the structural orientation of their binding domains.
The antifouling paint is comprised of a silyl ester copolymer containing constituent units derived from a polymerizable unsaturated carboxylic acid silyl ester, a carboxylic acid, a bivalent or trivalent metal compound, and a dehydrating agent.
In classical, bivalent logic the principal quantifiers are all and some.
Arguing that bivalent, rigid, and deterministic Western thought has its roots in nineteenth-century logic that was clear-cut with no shades of gray, Demastes notes that Artand turned to Eastern thought, which was multivalent and more sensory oriented.
For example, a typical transitive verb such as mangiare is said to have a valency of 2, or to be bivalent, since it requires both a subject and a direct object (2 arguments).