Dictionary » P » Prophase




The first phase of cell divisions (i.e. mitosis and meiosis), and in which during this phase the chromatin condenses (becoming more visible under a light microscope at high magnification) and initiating spindle formation


Cell divisions in eukaryotes, particularly mitosis and meiosis, are important since they give rise to new cells. Mitosis produces two cells that are genetically identical. Meiosis produces four cells that are genetically dissimilar and in which the chromosomes are reduced by half. Both mitosis and meiosis are comprised of chronological phases that start at prophase (followed by metaphase, anaphase, and finally by telophase). In meiosis though the prophase occurs twice, thus, the terms prophase I and prophase II.

During prophase of mitosis, and prophase I and prophase II of meiosis, the chromatin condenses, becoming more visible. This process is called chromatin condensation. The chromatin fibers condense to become distinct chromosomes that are visible when viewed under the light microscope at high magnification. Spindle formation begins and the nucleolus seems to disappear.

In meiosis, prophase I is comprised of the following sub-stages:

Word origin: Latin or Greek pró (before) + phase

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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: 4934

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
Wed Oct 16, 2013 9:36 am
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Re: Mitosis and meiosis!

The difference is not on the S phase. The differences are the meiosis is the reduction of chromosomes number compared parent cell. In Meiosis Prophase I is different from Prophase in mitosis where there is crossing over occur. In Metaphase I, the homologous chromosomes are aligned at the equatorial ...

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

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

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by Satyaki
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