Meiosis

meioticsyzygymeiosis Imeiosis IIprophase Imetaphase Ipachytenemetaphase IImeioticallydiakinesis
Meiosis (from Greek μείωσις, meiosis, which means lessening) is a specialized 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 specialized 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.

Eukaryote

eukaryoticeukaryotesEukaryota
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.

Cell division

divisiondaughter cellcellular division
Meiosis (from Greek μείωσις, meiosis, which means lessening) is a specialized 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).

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 G2-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

animalsmetazoanmetazoa
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.

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.

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.

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.

Mitosis

mitoticmitosesmitotic division
Although the process of meiosis is related to the more general cell division process of mitosis, it differs in two important respects:
Important exceptions include the gametes – sperm and egg cells – which are produced by meiosis.

Spindle apparatus

mitotic spindlespindlespindle pole
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

sporessporulationsporulating
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 cells
In female animals, three of the four meiotic products are typically eliminated by extrusion into polar bodies, and only one cell develops to produce an ovum.
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 specialized 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 for humans (half of 46) is 23; and the monoploid number equals 46 divided by the ploidy level of 2, which is also 23. When a human germ cell undergoes meiosis, the two sets of 23 chromosomes are split in half to form gametes.

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.

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.

Synapsis

presynapticsynapsedsynaptic
The process of pairing the homologous chromosomes is called synapsis.
Synapsis (also called syndesis) is the pairing of two homologous chromosomes that occurs during meiosis.

Interphase

Interphase is divided into three phases:
In interphase, the cell gets itself ready for mitosis or meiosis.

Interkinesis

In some species, cells enter a resting phase known as interkinesis between meiosis I and meiosis II.
Interkinesis or interphase II is a period of rest that cells of some species enter during meiosis, between meiosis I and meiosis II.