Ploidy

diploidhaploid2nchromosome numberdiploid numberdiploidytetraploiddiploidseuploidchromosome numbers
Ploidy is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes.wikipedia
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Autosome

autosomalautosomal DNAautosomes
Ploidy is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes.
The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosome pairs which may have different structures.

Sexual reproduction

sexuallysexualreproduce sexually
Virtually all sexually reproducing organisms are made up of somatic cells that are diploid or greater, but ploidy level may vary widely between different organisms, between different tissues within the same organism, and at different stages in an organism's life cycle.
Sexual reproduction is a type of life cycle where generations alternate between cells with a single set of chromosomes (haploid) and cells with a double set of chromosomes (diploid).

Meiosis

meioticsyzygymeiosis I
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).
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.

Allele

allelesallelicmultiple alleles
Ploidy is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes.
Most multicellular organisms have two sets of chromosomes; that is, they are diploid.

Fertilisation

fertilizationconceptionfertilized
After fusion of a male and a female gamete (each containing 1 set of 23 chromosomes) during fertilization, the resulting zygote again has the full complement of 46 chromosomes: 2 sets of 23 chromosomes.
During double fertilisation in angiosperms the haploid male gamete combines with two haploid polar nuclei to form a triploid primary endosperm nucleus by the process of vegetative fertilisation.

Sperm

sperm cellspermatiasperm cells
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). Gametes (sperm and ova) are haploid cells.
The human sperm cell is haploid, so that its 23 chromosomes can join the 23 chromosomes of the female egg to form a diploid cell.

Eukaryote

Eukaryotaeukaryoticeukaryotes
In this case, the nucleus of a eukaryotic cell is only said to be haploid if it has a single set of chromosomes, each one not being part of a pair.
In meiosis, DNA replication is followed by two rounds of cell division to produce four haploid daughter cells.

Egg cell

ovumovaegg
Gametes (sperm and ova) are haploid cells.
When egg and sperm fuse, a diploid cell (the zygote) is formed, which rapidly grows into a new organism.

Alternation of generations

alternation of generationalternatingdiplohaplontic
This is called alternation of generations.
In these groups, a multicellular gametophyte, which is haploid with n chromosomes, alternates with a multicellular sporophyte, which is diploid with 2n chromosomes, made up of n pairs.

Haplodiploidy

haplodiploidhaplodiploid sex-determination systemhaplo-diploid
Most animals are diploid, but male bees, wasps, and ants are haploid organisms because they develop from unfertilized, haploid eggs, while females (workers and queens) are diploid, making their system haplodiploid.
Haplodiploidy is a sex-determination system in which males develop from unfertilized eggs and are haploid, and females develop from fertilized eggs and are diploid.

Chromosome

chromosomeschromosomalChromosomal number
Ploidy is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. In this case, the nucleus of a eukaryotic cell is only said to be haploid if it has a single set of chromosomes, each one not being part of a pair.
For example, most eukaryotes are diploid, like humans who have 22 different types of autosomes, each present as two homologous pairs, and two sex chromosomes.

Moss

mossesBryophytaMusci
Most fungi and algae are haploid during the principal stage of their life cycle, as are some primitive plants like mosses.
Mosses were formerly grouped with the hornworts and liverworts as "non-vascular" plants in the division "bryophytes", all of them having the haploid gametophyte generation as the dominant phase of the life cycle.

Fungus

Fungifungalnecrotrophic
All plants and many fungi and algae switch between a haploid and a diploid state, with one of the stages emphasized over the other.
Most fungi have both a haploid and a diploid stage in their life cycles.

Zygote

zygoticzygotesfertilized egg
After fusion of a male and a female gamete (each containing 1 set of 23 chromosomes) during fertilization, the resulting zygote again has the full complement of 46 chromosomes: 2 sets of 23 chromosomes.
In plants, the zygote may be polyploid if fertilization occurs between meiotically unreduced gametes.

Human genome

genomehuman DNAhuman geneticist
Human diploid cells have 46 chromosomes (the somatic number, 2n) and human haploid gametes (egg and sperm) have 23 chromosomes (n).
Haploid human genomes, which are contained in germ cells (the egg and sperm gamete cells created in the meiosis phase of sexual reproduction before fertilization creates a zygote) consist of three billion DNA base pairs, while diploid genomes (found in somatic cells) have twice the DNA content.

Gamete

gametesgameticreproductive cells
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). Gametes (sperm and ova) are haploid cells. Human diploid cells have 46 chromosomes (the somatic number, 2n) and human haploid gametes (egg and sperm) have 23 chromosomes (n).
A gamete (from Ancient Greek γαμετή gamete from gamein "to marry" ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that sexually reproduce.

Plant

Plantaeplantsflora
All plants and many fungi and algae switch between a haploid and a diploid state, with one of the stages emphasized over the other.
This involves an alternation between two generations: a haploid stage, called the gametophyte, and a diploid stage, called the sporophyte.

Cell (biology)

cellcellscellular
Ploidy is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes.
A diploid cell may also undergo meiosis to produce haploid cells, usually four.

Homologous chromosome

homologshomologous chromosomeshomologous
The chromosomes in each pair, one of which comes from the sperm and one from the egg, are said to be homologous.
In diploid (2n) organisms, the genome is composed of one set of each homologous chromosome pair, as compared to tetraploid organisms which may have two sets of each homologous chromosome pair.

Somatic cell

somatic cellssomaticvegetative cell
Somatic cells, tissues, and individual organisms can be described according to the number of sets of chromosomes present (the "ploidy level"): monoploid (1 set), diploid (2 sets), triploid (3 sets), tetraploid (4 sets), pentaploid (5 sets), hexaploid (6 sets), heptaploid or septaploid (7 sets), etc. The generic term polyploid is often used to describe cells with three or more chromosome sets.
If a somatic cell contains chromosomes arranged in pairs, it is called diploid and the organism is called a diploid organism.

Germ cell

germ cellsprimordial germ cellssex cells
When a human germ cell undergoes meiosis, the diploid 46-chromosome complement is split in half to form haploid gametes.
The secondary oocyte undergoes meiotic division II and that results in the formation of a second small polar body and a large mature egg, both being haploid cells.

Gene

genesnumber of genesgene sequence
Ploidy is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes.
In sexually reproducing organisms, a specialized form of cell division called meiosis produces cells called gametes or germ cells that are haploid, or contain only one copy of each gene.

Somatic (biology)

somaticsomasomatic cells
Human diploid cells have 46 chromosomes (the somatic number, 2n) and human haploid gametes (egg and sperm) have 23 chromosomes (n).
These somatic cells are diploid containing two copies of each chromosome, whereas the germ cells are haploid as they only contain one copy of each chromosome.

Golden viscacha rat

PipanacoctomysPipanacoctomys aureusP. aureus
The suspected tetraploid (possessing four chromosome sets) plains viscacha rat (Tympanoctomys barrerae) and golden viscacha rat (Pipanacoctomys aureus) have been regarded as the only known exceptions (as of 2004).
It has 92 chromosomes and has been regarded as tetraploid (4x = 2n).

Triangle of U

3 major ancestral genomesBrassica'' triangleoriginated
The so-called Brassica triangle is an example of allopolyploidy, where three different parent species have hybridized in all possible pair combinations to produce three new species.
The theory states that the genomes of three ancestral diploid species of Brassica combined to create three common tetraploid vegetables and oilseed crop species.