Search results
Results from the WOW.Com Content Network
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.
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.
So, humans have two sets of 23 chromosomes in each cell that contains a nucleus. One set of 23 chromosomes (n) is from the mother (22 autosomes, 1 sex chromosome (X only)) and one set of 23 chromosomes (n) is from the father (22 autosomes, 1 sex chromosome (X or Y)). Ultimately, this means that humans are diploid (2n) organisms. [2]
Human diploid cells have 46 chromosomes (the somatic number, 2n) and human haploid gametes (egg and sperm) have 23 chromosomes (n). Retroviruses that contain two copies of their RNA genome in each viral particle are also said to be diploid. Examples include human foamy virus, human T-lymphotropic virus, and HIV. [29]
Another study found green eyes, which are a result of lower melanin levels, to be much more common in females than in males, at least by a factor of two. [55] [56] A different study found that while females tend to have a lower frequency of black hair, males have a higher frequency of platinum blond hair, blue eyes and lighter skin.
Ploidy/Chromosomes in human DNA copy number/Chromatids in human Process entered by cell Duration spermatogonium (types Ad, Ap and B) germ cells: diploid (2N) / 46: 2C / 46: spermatocytogenesis : 16 days primary spermatocyte: male gametocyte: diploid (2N) / 46: 4C / 2x46: spermatocytogenesis : 24 days secondary spermatocyte: male gametocyte ...
ploidy/chromosomes in human: DNA copy number/chromatids in human: Process entered by cell: spermatogonium (types Ad, Ap and B) diploid (2N) / 46: 2C / 46: spermatocytogenesis primary spermatocyte: diploid (2N) / 46: 4C / 2x46: spermatidogenesis (meiosis I) two secondary spermatocytes: haploid (N) / 23: 2C / 2x23: spermatidogenesis (meiosis II ...
Polyploidy occurs in some tissues of animals that are otherwise diploid, such as human muscle tissues. [45] This is known as endopolyploidy. Species whose cells do not have nuclei, that is, prokaryotes, may be polyploid, as seen in the large bacterium Epulopiscium fishelsoni. [46] Hence ploidy is defined with respect to a cell.