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Bivalent

Definition

noun, plural: bivalents

(genetics) A pair of homologous chromosomes in synapsis during meiosis.

adjective

(chemistry) Of, or having a valence of two; divalent.

(genetics) Of, or pertaining to the bivalent structure or the association of the two homologous chromosomes during meiosis.


Supplement

In genetics, a bivalent refers to the two homologous chromosomes that have already joined or paired together in synapsis at Prophase I of Meiosis I.

Word origin: bi- (two) + valent from valence
Related forms: bivalence (noun)

Compare: univalent, polyvalent

See also: valence

Related terms:


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Meiosis division

... cells. In meiosis i believe that DNA replication occurs, making 72 which then divides into 46 in two cells. These cells have the crossed over bivalent pairs. But from what i have read it is said that after this first division there are 2 haploid cells? How can this be if there are 2n chromosomes ...

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by ALevelBio
Mon Apr 09, 2012 12:39 pm
 
Forum: Cell Biology
Topic: Meiosis division
Replies: 1
Views: 1651

Questions re crossing over and histones

A question I encountered is asking to demonstrate using a diagram of a bivalent of the F1 progeny with a single crossing over event causing all the produced gametes to be parental? I don't get how this works because I thought crossing over would have resulted ...

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by dawn1070
Wed Jun 16, 2010 6:41 am
 
Forum: Genetics
Topic: Questions re crossing over and histones
Replies: 3
Views: 2123

Chromosome segregation

... specify in prophase I (subphase: pachytene), and consists of the intersection of two of the four chromatids of homologous chromosomes to form a bivalent, beginning the interbreeding with rupture of the two double DNA chains and subsequent alternative splicing, joining in a single fiber of the ...

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by Fidias
Mon Jun 07, 2010 4:46 pm
 
Forum: Cell Biology
Topic: Chromosome segregation
Replies: 1
Views: 2606

Questions about Biology's term

... So during metaphase the two halves of a copied chromosome are both chromatids. At anaphase these separate and become two new chromosomes. Bivalent: A chromosome that has duplicated to form two sister chromatids still held together at the centromere. Tetrads: Group of four chromatids at ...

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by Jesse2504
Tue Jun 23, 2009 6:25 am
 
Forum: General Discussion
Topic: Questions about Biology's term
Replies: 6
Views: 7080

Questions about Biology's term

What is the difference between chromatid, chromatin and chromosome? It also state that bivalent is visible under microscope as a 4 part structure called tetrad. Is this means that bivalent is also tetrad? My text book state that homologous chromosome consist of 2 chromosome(1 ...

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by dorevidadamn
Sun Jun 21, 2009 2:53 am
 
Forum: General Discussion
Topic: Questions about Biology's term
Replies: 6
Views: 7080
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