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The list of organisms by chromosome count describes ploidy or numbers of chromosomes in the cells of various plants, animals, protists, and other living organisms.This number, along with the visual appearance of the chromosome, is known as the karyotype, [1] [2] [3] and can be found by looking at the chromosomes through a microscope.
Euploidy and aneuploidy describe having a number of chromosomes that is an exact multiple of the number of chromosomes in a normal gamete; and having any other number, respectively. For example, a person with Turner syndrome may be missing one sex chromosome (X or Y), resulting in a (45,X) karyotype instead of the usual (46,XX) or (46,XY).
The basic number of chromosomes in the somatic cells of an individual or a species is called the somatic number and is designated 2n. In the germ-line (the sex cells) the chromosome number is n (humans: n = 23). [4] [5] p28 Thus, in humans 2n = 46. So, in normal diploid organisms, autosomal chromosomes are present in two copies.
[1] [2] By analysing the similarities and differences in the chromosomes, karyotype evolution and species evolution can be reconstructed. The number, structure, and behaviour of chromosomes is of great value in taxonomy , with chromosome number being the most widely used and quoted character.
That is two full genome sets (one A and one C), hence "2n=38" which means "n=19" (the number of chromosomes in each gamete). It is also four component genomes (two A and two C), hence "4x=38". [2] The three diploid species exist in nature, but can easily interbreed because they are closely related.
The naming of hybrid animals depends on the sex and species of the parents. The father giving the first half of his species' name and the mother the second half of hers. (I.e. a pizzly bear has a polar bear father and grizzly bear mother whereas a grolar bear's parents would be reversed.)
Polyploidy is a condition in which the cells of an organism have more than two paired sets of chromosomes. Most species whose cells have nuclei are diploid, meaning they have two complete sets of chromosomes, one from each of two parents; each set contains the same number of chromosomes, and the chromosomes are joined in pairs of homologous ...
The ZW sex-determination system is a chromosomal system that determines the sex of offspring in birds, some fish and crustaceans such as the giant river prawn, some insects (including butterflies and moths), the schistosome family of flatworms, and some reptiles, e.g. majority of snakes, lacertid lizards and monitors, including Komodo dragons.