Meiosis

meioticsyzygymeiosis Imeiosis IIprophase Imetaphase Ipachytenemetaphase IImeioticallyreduction division
Meiosis (from Greek μείωσις, meiosis, which means lessening) is a special type of cell division that reduces the chromosome number by half, creating four haploid cells, each genetically distinct from the parent cell that gave rise to them.wikipedia
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Sexual reproduction

sexuallysexualreproduce sexually
This process occurs in all sexually reproducing single-celled and multicellular eukaryotes, including animals, plants, and fungi.
Diploid cells divide into haploid cells in a process called meiosis.

Chromosome

chromosomeschromosomalChromosomal number
Meiosis (from Greek μείωσις, meiosis, which means lessening) is a special type of cell division that reduces the chromosome number by half, creating four haploid cells, each genetically distinct from the parent cell that gave rise to them.
Chromosomal recombination during meiosis and subsequent sexual reproduction play a significant role in genetic diversity.

Cell division

divisiondaughter cellcellular division
Meiosis (from Greek μείωσις, meiosis, which means lessening) is a special type of cell division that reduces the chromosome number by half, creating four haploid cells, each genetically distinct from the parent cell that gave rise to them.
In eukaryotes, there are two distinct types of cell division: a vegetative division, whereby each daughter cell is genetically identical to the parent cell (mitosis), and a reproductive cell division, whereby the number of chromosomes in the daughter cells is reduced by half to produce haploid gametes (meiosis).

Eukaryote

Eukaryotaeukaryoticeukaryotes
This process occurs in all sexually reproducing single-celled and multicellular eukaryotes, including animals, plants, and fungi.
Eukaryotes can reproduce both asexually through mitosis and sexually through meiosis and gamete fusion.

Aneuploidy

aneuploidaneuploidiesdisomy
Errors in meiosis resulting in aneuploidy are the leading known cause of miscarriage and the most frequent genetic cause of developmental disabilities.
During meiosis, when germ cells divide to create sperm and egg (gametes), each half should have the same number of chromosomes.

Genetic recombination

recombinationmeiotic recombinationDNA recombination
During this time, homologous chromosomes pair with each other and undergo genetic recombination, a programmed process in which DNA is cut and then repaired, which allows them to exchange some of their genetic information.
In eukaryotes, genetic recombination during meiosis can lead to a novel set of genetic information that can be passed on from the parents to the offspring.

Prophase

chromatin condensation
Immediately following DNA replication, meiotic cells enter a prolonged G 2 -like stage known as meiotic prophase. Meiosis I and II are each divided into prophase, metaphase, anaphase, and telophase stages, similar in purpose to their analogous subphases in the mitotic cell cycle.
]]Prophase (from the Greek πρό, "before" and φάσις, "stage") is the first stage of cell division in both mitosis and meiosis.

Animal

Animaliaanimalsmetazoa
This process occurs in all sexually reproducing single-celled and multicellular eukaryotes, including animals, plants, and fungi.
They produce haploid gametes by meiosis; the smaller, motile gametes are spermatozoa and the larger, non-motile gametes are ova.

Oogenesis

ootidogenesisoocyte maturationOocytogenesis
Meiotic cell divisions are an essential process during oogenesis and spermatogenesis.
However, although this process begins at prenatal age, it stops at prophase I.

Homologous recombination

recombinationrecombinational repairhomolog recombination
Then each set of homologs pair with each other and exchange DNA by homologous recombination leading to physical connections (crossovers) between the homologs.
Homologous recombination also produces new combinations of DNA sequences during meiosis, the process by which eukaryotes make gamete cells, like sperm and egg cells in animals.

Homologous chromosome

homologshomologous chromosomeshomologous
During this time, homologous chromosomes pair with each other and undergo genetic recombination, a programmed process in which DNA is cut and then repaired, which allows them to exchange some of their genetic information.
A couple of homologous chromosomes, or homologs, are a set of one maternal and one paternal chromosome that pair up with each other inside a cell during meiosis.

Mitosis

mitoticmitosesmitotic division
During Meiosis II, the cohesion between sister chromatids is released and they segregate from one another, as during mitosis.
Important exceptions include the gametes – sperm and egg cells – which are produced by meiosis.

Chromosome segregation

chromosomal segregationsegregationsegregate
In most organisms, these links are essential to direct each pair of homologous chromosomes to segregate away from each other during Meiosis I, resulting in two haploid cells that have half the number of chromosomes as the parent cell.
This segregation process occurs during both mitosis and meiosis.

Spermatogenesis

spermatogenicsperm productionproduction of sperm
Meiotic cell divisions are an essential process during oogenesis and spermatogenesis.
The protein FMRP binds to meiotic chromosomes and regulates the dynamics of the DDR machinery during spermatogenesis.

Pollen

exinepollen grainmicrosporogenesis
In some cases all four of the meiotic products form gametes such as sperm, spores, or pollen.
In a process called microsporogenesis, four haploid microspores are produced from each diploid sporogenous cell (microsporocyte, pollen mother cell or meiocyte), after meiotic division.

Spindle apparatus

mitotic spindlespindlemitotic apparatus
In the first meiotic division, the homologs are segregated to separate daughter cells by the spindle apparatus.
It is referred to as the mitotic spindle during mitosis, a process that produces genetically identical daughter cells, or the meiotic spindle during meiosis, a process that produces gametes with half the number of chromosomes of the parent cell.

Parthenogenesis

parthenogeneticparthenogenicparthenogenetically
Some eukaryotes, like bdelloid rotifers, do not have the ability to carry out meiosis and have acquired the ability to reproduce by parthenogenesis.
Normal egg cells form after meiosis and are haploid, with half as many chromosomes as their mother's body cells.

Spore

sporessporulationsporulate
In some cases all four of the meiotic products form gametes such as sperm, spores, or pollen.
Spores are usually haploid and unicellular and are produced by meiosis in the sporangium of a diploid sporophyte.

Sperm

sperm cellspermatiasperm cells
In some cases all four of the meiotic products form gametes such as sperm, spores, or pollen.
The spermatozoa of animals are produced through spermatogenesis inside the male gonads (testicles) via meiotic division.

Chiasma (genetics)

chiasmachiasmatachiasma (plural: chiasmata)
A subset of recombination events results in crossovers, which create physical links known as chiasmata (singular: chiasma, for the Greek letter Chi (X)) between the homologous chromosomes.
At a given chiasma, an exchange of genetic material can occur between both chromatids, what is called a chromosomal crossover, but this is much more frequent during meiosis than mitosis.

Polar body

polar bodiespolar bodyspolar cells
In female animals, three of the four meiotic products are typically eliminated by extrusion into polar bodies, and only one cell develops to
When certain diploid cells in animals undergo cytokinesis after meiosis to produce egg cells, they sometimes divide unevenly.

Ploidy

diploidhaploid2n
Meiosis (from Greek μείωσις, meiosis, which means lessening) is a special type of cell division that reduces the chromosome number by half, creating four haploid cells, each genetically distinct from the parent cell that gave rise to them. In most organisms, these links are essential to direct each pair of homologous chromosomes to segregate away from each other during Meiosis I, resulting in two haploid cells that have half the number of chromosomes as the parent cell.
The haploid number (n) refers to the total number of chromosomes found in a gamete (a sperm or egg cell produced by meiosis in preparation for sexual reproduction).

Telophase

nuclear division
Meiosis I and II are each divided into prophase, metaphase, anaphase, and telophase stages, similar in purpose to their analogous subphases in the mitotic cell cycle.
Telophase (from the Greek τέλος (télos), "end" and φάσις (phásis), "stage") is the final stage in both meiosis and mitosis in a eukaryotic cell.

Fission (biology)

binary fissionfissionschizogony
Meiosis does not occur in archaea or bacteria, which generally reproduce asexually via binary fission.
Unlike the processes of mitosis and meiosis used by eukaryotic cells, binary fission takes place without the formation of a spindle apparatus on the cell.

Chromosomal crossover

crossing overcrossovercrossing-over
A subset of recombination events results in crossovers, which create physical links known as chiasmata (singular: chiasma, for the Greek letter Chi (X)) between the homologous chromosomes.
It is one of the final phases of genetic recombination, which occurs in the pachytene stage of prophase I of meiosis during a process called synapsis.