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Prophase I

Definition

noun

The first stage in the first meiotic division of meiosis. This stage is characterized by having five sub-stages namely leptotene, zygotene, pachytene, diplotene and diakinesis. It highlights the exchange of DNA between homologous chromosomes via a process called homologous recombination and the cross-over at chiasma(ta) between non-sister chromatids. Thus, this stage is important to increase genetic variation. This stage then ends with the disintegration of the nucleolus and the nuclear membrane.


Supplement

Since meiosis consists of two consecutive nuclear divisions, prophase occurs twice. Thus, there are prophase I and prophase II.


See also: prophase II, meiosis I


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Meiosis prophase I crossover

“Chromosomal crossover (or crossing over) is the exchange of genetic material between homologous chromosomes that results in recombinant chromosomes.” http://en.wikipedia.org/wiki/Chromosomal_crossover Question: Due to the multiple layers of winding, how can parts of the chromosome break evenly? Is ...

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by gs99
Fri Mar 07, 2014 9:23 pm
 
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Topic: Meiosis prophase I crossover
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Views: 201

Re: Year 11 Meiosis helpp!!!

During the first part of meiosis (prophase 1) there can be recombination (crossover) of homologous chromosomes. This would show up on your diagram as being a little bit of red on one arm of the blue X, and a matching little bit of blue in ...

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by ChrisHoStuart
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Re: Mitosis and meiosis!

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by mavis
Wed Jan 30, 2013 9:00 am
 
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Re: Crossing Over

... in meiosis happens during metaphase 1. I asked her about this, pointing out the evidence that I had that said that crossing over happens during prophase 1. She says that the line between prophase and metaphase are obscure and that the actual event happens during metaphase. What does anyone have ...

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by LadyAmalara
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Re: Compare and contrast the processes of Mitosis and Meiosis

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