Dictionary » M » Meiosis




A form of cell division happening in sexually reproducing organisms by which two consecutive nuclear divisions (meiosis I and meiosis II) occur without the chromosomal replication in between, leading to the production of four haploid gametes (sex cells), each containing one of every pair of homologous chromosomes (that is, with the maternal and paternal chromosomes being distributed randomly between the cells).


Meiosis encompasses interphase, meiosis I and meiosis II. The interphase consists of G1, S and G2 whereas both meiosis I and II consist of four major subphases such as prophase, metaphase, anaphase and telophase. The process of meiosis is briefly described as follows. During the interphase, the chromosomes in a cell are duplicated. This is followed by meiosis I wherein the chromosomes condense along the center of the nucleus, and pair with their homologues during crossing over. Next, the pairs of chromosomes separate and move to opposite ends of the cell. The cell divides for the first time producing two cells. The two cells will undergo meiosis II wherein both of them divides further into two cells, each containing one of every decoupled chromosome’s sister strands (chromatids), thus, producing four genetically different, haploid cells.

Meiosis is a vital process because it reduces the original number of chromosomes to half, and allows genetic variability by genetic recombination and independent assortment. Meiosis produces four haploid cells that may develop into potential gametes so that when fertilization occurs, a new individual with the full number of genes results, thereby maintaining the integrity of chromosomal number across generations while promoting genetic diversity and variability in forms in the population.

Word origin: Greek meiōsis, diminution, from meioun, to diminish, from meiōn, less.
Related forms: meiotic (adjective).

Compare: mitosis.
See also: cell division.

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I need help with this please? Provide a genetic explain for why when diploid yeast cells are sporulated (undergo meiosis), the resulting haploids were ALL tolerant to ethanol??? :D

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by leroymelo
Fri Nov 14, 2014 9:08 pm
Forum: General Discussion
Topic: Yeast
Replies: 0
Views: 475

Colorblindness Probability Help!

... is about 1 in every 1000 male births, the extra X chromosome coming either from the mother's egg or the father's sperm by nondisjunction during meiosis. Suppose the baby's father has red-green colorblindness. Would you predict that the baby boy with an XXY karyotype would also be colorblind, ...

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by kaylagh
Sun Sep 07, 2014 6:07 am
Forum: Genetics
Topic: Colorblindness Probability Help!
Replies: 0
Views: 1431

mitosis and miosis

In a nutshell: Mitosis- The division of a cell to create two identical new cells. Meiosis- The division of a cell into a gamete, carrying half the genetic DNA of a normal cell, to fertilize another gamete (Example, sperm fertilizing an egg)

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by CaptainCovalency
Thu Jul 10, 2014 3:58 am
Forum: Cell Biology
Topic: mitosis and miosis
Replies: 2
Views: 4047


... are possible in daughter cells following mitosis? b. What combination(s) of chromosomes are possible in haploid cells following both divisions of meiosis? (Hint: remember independent assortment)

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by lachatausa
Fri Mar 21, 2014 2:55 am
Forum: Genetics
Topic: genetic
Replies: 1
Views: 4228

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
Forum: Molecular Biology
Topic: Meiosis prophase I crossover
Replies: 0
Views: 4975
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