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Encyclopedia > Chromosome

For information about chromosomes in genetic algorithms, see chromosome (genetic algorithm). A genetic algorithm (GA) is a search technique used in computing to find exact or approximate solutions to optimization and search problems. ... In genetic algorithms, a chromosome (also sometimes called a genome) is a set of parameters which define a proposed solution to the problem that the genetic algorithm is trying to solve. ...

Diagram of a duplicated and condensed (metaphase) eukaryotic chromosome. (1) Chromatid - one of the two identical parts of the chromosome after S phase. (2) Centromere - the point where the two chromatids touch, and where the microtubules attach. (3) Short arm. (4) Long arm.
Diagram of a duplicated and condensed (metaphase) eukaryotic chromosome. (1) Chromatid - one of the two identical parts of the chromosome after S phase. (2) Centromere - the point where the two chromatids touch, and where the microtubules attach. (3) Short arm. (4) Long arm.

Chromosomes are organized structures of DNA and proteins that are found in cells. A chromosome is a singular piece of DNA, which contains many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions. The word chromosome comes from the Greek χρῶμα (chroma, color) and σῶμα (soma, body) due to their property of being stained very strongly by some dyes. Animation of a section of DNA rotating. ... Image File history File links No higher resolution available. ... An image of a newt lung cell stained with fluorescent dyes during metaphase. ... A chromatid forms one part of a chromosome after it has coalesced for the process of mitosis or meiosis. ... DNA replication. ... Chromosome. ... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... A representation of the 3D structure of myoglobin showing coloured alpha helices. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... For other uses, see Gene (disambiguation). ... A regulatory sequence (also called regulatory region or ~ element) is a promoter, enhancer or other segment of DNA where regulatory proteins such as transcription factors bind preferentially. ... A DNA sequence (sometimes genetic sequence) is a succession of letters representing the primary structure of a real or hypothetical DNA molecule or strand, The possible letters are A, C, G, and T, representing the four nucleotide subunits of a DNA strand (adenine, cytosine, guanine, thymine), and typically these are... A dye can generally be described as a coloured substance that has an affinity to the substrate to which it is being applied. ...


Chromosomes vary extensively between different organisms. The DNA molecule may be circular or linear, and can contain anything from tens of kilobase pairs to hundreds of megabase pairs. Typically eukaryotic cells (cells with nuclei) have large linear chromosomes and prokaryotic cells (cells without defined nuclei) have smaller circular chromosomes, although there are many exceptions to this rule. Furthermore, cells may contain more than one type of chromosome; for example mitochondria in most eukaryotes and chloroplasts in plants have their own small chromosomes. Domains and Kingdoms Nanobes Acytota Cytota Bacteria Neomura Archaea Eukaryota Bikonta Apusozoa Rhizaria Excavata Archaeplastida Rhodophyta Glaucophyta Plantae Heterokontophyta Haptophyta Cryptophyta Alveolata Unikonta Amoebozoa Opisthokonta Choanozoa Fungi Animalia An ericoid mycorrhizal fungus Life on Earth redirects here. ... A unit of measurement in molecular biology denoting a length of 1000 nucleotides (bases) of DNA or RNA. Categories: | ... Megabase (Mb) is a unit of length for DNA fragments, equal to 1 million nucleotides. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Chromalveolata Protista Alternative phylogeny Unikonta Opisthokonta Metazoa Choanozoa Eumycota Amoebozoa Bikonta Apusozoa Cabozoa Rhizaria Excavata Corticata Archaeplastida Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms whose cells are organized into complex structures by internal membranes and a cytoskeleton. ... Prokaryotes are unicellular (in rare cases, multicellular) organisms without a nucleus. ... In cell biology, a mitochondrion is an organelle found in the cells of most eukaryotes. ... Kingdoms Eukaryotes are organisms with complex cells, in which the genetic material is organized into membrane-bound nuclei. ... Chloroplasts are organelles found in plant cells and eukaryotic algae which conduct photosynthesis. ...


In eukaryotes, nuclear chromosomes are packaged by proteins into a condensed structure called chromatin. This allows the massively-long DNA molecules to fit into the cell nucleus. The structure of chromosomes and chromatin varies through the cell cycle. Chromosomes may exist as either duplicated or unduplicated—unduplicated chromosomes are single linear strands, while duplicated chromosomes (copied during S phase) contain two copies joined by a centromere. Compaction of the duplicated chromosomes during mitosis and meiosis results in the classic four-arm structure (pictured to the right). Chromatin is the complex of DNA and protein found inside the nuclei of eukaryotic cells. ... HeLa cells stained for DNA with the Blue Hoechst dye. ... The cell cycle, or cell-division cycle, is the series of events that take place in a eukaryotic cell leading to its replication. ... DNA replication. ... Chromosome. ... Mitosis divides genetic information during cell division. ... For the figure of speech, see meiosis (figure of speech). ...


"Chromosome" is a rather loosely defined term. In prokaryotes, a small circular DNA molecule may be called either a plasmid or a small chromosome. These small circular genomes are also found in mitochondria and chloroplasts, reflecting their bacterial origins. The simplest chromosomes are found in viruses: these DNA or RNA molecules are short linear or circular chromosomes that often lack any structural proteins. Figure 1: Illustration of a bacterium with plasmids enclosed showing chromosomal DNA and plasmids. ... Stop editing pages god ...

Contents

History

This is a brief history of research in a complex field where each advance was hard won, and often hotly disputed at the time.


Visual discovery of chromosomes. Textbooks have often said that chromosomes were first observed in plant cells by a Swiss botanist named Karl Wilhelm von Nägeli in 1842.[1] However, this opinion has been challenged, perhaps decisively, by Henry Harris, who has freshly reviewed the primary literature.[2] In his opinion the claim of Nägeli to have seen spore mother cells divide is mistaken, as are some of his interpretations. Harris considers other candidates, especially Wilhelm Hofmeister, whose publications in 1848-9 include plates which definitely show mitotic events.[3][4] Hofmeister was also the choice of Cyril Darlington. For other uses, see Plant (disambiguation). ... Botany is the scientific study of plant life. ... Karl Wilhelm von Nägeli (March 27, 1817 - May 11, 1891) was a Swiss botanist. ... 1842 was a common year starting on Saturday (see link for calendar). ... Wilhelm Friedrich Benedikt Hofmeister (18 May 1824 to 12 January 1877) was a German self-taught botanist. ... Professor Cyril Dean Darlington FRS (19 December 1903 - 26 March 1981) was a British biologist, who, with Ronald Fisher established the journal Heredity. ...


The work of other cytologists such as Walther Flemming, Eduard Strasburger, Otto Bütschli, Oskar Hertwig and Carl Rabl should definitely be acknowledged. The use of basophilic aniline dyes was a new technique for effectively staining the chromatin material in the nucleus. Their behavior in animal (salamander) cells was later described in detail by Walther Flemming, who in 1882 "provided a superb summary of the state of the field".[5][6] The name chromosome was invented in 1888 by Heinrich von Waldeyer. However, van Beneden's monograph of 1883 on the fertilised eggs of the parasitic roundworm Ascaris megalocephala was the outstanding work of this period.[7] His conclusions are classic: Illustrations of cells with chromosomes and mitosis, from the book Zell-substanz, Kern und Zelltheilung, 1882 Walther Flemming (born April 21, 1843 in Sachsenberg, Germany; died August 4, 1905 in Kiel) was a founder of the study of cytogenetics. ... Eduard Adolf Strasburger (February 1, 1844, Warsaw - May 19, 1912, Bonn) was one of the most famous German botanists of the 19th century. ... Otto Bütschli (1848-1920) was a German zoologist and professor at the University of Heidelberg. ... Oskar Hertwig (April 21, 1849, Friedberg, Hessen - October 25, 1922, Berlin) was a German zoologist. ... Basophilic is a technical term used by histologists. ... Aniline, phenylamine or aminobenzene is an organic compound with the formula C6H5NH2. ... Look up dye in Wiktionary, the free dictionary. ... ... Chromatin is the complex of DNA and protein found inside the nuclei of eukaryotic cells. ... For other uses, see Salamander (disambiguation). ... Illustrations of cells with chromosomes and mitosis, from the book Zell-substanz, Kern und Zelltheilung, 1882 Walther Flemming (born April 21, 1843 in Sachsenberg, Germany; died August 4, 1905 in Kiel) was a founder of the study of cytogenetics. ... Heinrich Wilhelm Gottfried von Waldeyer-Hartz (born October 6, 1836, Hehlen an der Weser, Braunschweig, Germany; died January 23, 1921, Berlin) was a German anatomist, famous for consolidating the neuron theory of organization of the nervous system and for naming the chromosome. ... Species Ascaris lumbricoides Ascaris suum Ascaris is a genus of parasitic nematodes. ...

  • Thus there is no fusion between the male chromatin and the female chromatin at any stage of division...
  • The elements of male origin and those of female origin are never fused together in a cleavage nucleus, and perhaps they remain distinct in all the nuclei derived from them. [tranl: Harris p162]

"It is not easy to identify who first discerned chromosomes during mitosis, but there is no doubt that those who first saw them had no idea of their significance... [but] with the work of Balbiani and van Beneden we move away from... the mechanism of cell division to a precise delineation of chromosomes and what they do during the division of the cell." [8] Edouard-Gérard Balbiani (July 31, 1823 - July 25, 1899 was a French embryologist who was born in Port-au-Prince, Haiti. ... Edouard Van Beneden (1846-1910) was a professor of zoology at the university of Liège; he has been at the basis of the genetic studies of the 20th century, thanks to his works on a parasite of the horse, that made him discover how chromosomes combined during reproduction. ...

Van Beneden's master work was closely followed by that of Carl Rabl, who reached similar conclusions. [9] This more or less concludes the first period, in which chromosomes were visually sighted, and the morphological stages of mitosis were described. Coleman also gives a useful review of these discoveries.[10]


Nucleus as the seat of heredity. The origin of this epoch-making idea lies in a few sentences tucked away in Ernst Haeckel's Generelle Morphologie of 1866.[11] The evidence for this insight gradually acumulated until, after twenty or so years, two of the greatest in a line of great German scientists spelt it out. August Weismann proposed that the germ line was separate from the soma, and that the cell nucleus was the repository of the hereditary material, which he proposed was arranged along the chromosomes in a linear manner. Furthermore, he proposed that at fertilisation a new combination of chromosomes (and their hereditary material) would be formed. This was the explanation for the reduction division of meiosis (first described by van Beneden). August Weismann Friedrich Leopold August Weismann (b. ... Germline is a word used in biology and genetics. ... This article does not cite any references or sources. ... For the figure of speech, see meiosis (figure of speech). ...


Chromosomes as vectors of heredity. In a series of outstanding experiments, Theodor Boveri gave the definitive demonstration that chromosomes were the vectors of heredity. His two principles were: Theodor Boveri (1862 – 1915) was a German biologist whose work with sea urchins showed that it was necessary to have all chromosomes present in order for proper embryonic development to take place. ...

The continuity of chromosomes
The individuality of chromosomes.

It was the second of these principles which was so original. He was able to test the proposal put forward by Wilhelm Roux, that each chromosome carries a different genetic load, and showed that Roux was right. Upon the rediscovery of Mendel, Boveri was able to point out the connection between the rules of inheritance and the behaviour of the chromosomes. It is interesting to see that Boveri influenced two generations of American cytologists: Edmund Beecher Wilson, Walter Sutton and Theophilus Painter were all influenced by Boveri (Wilson and Painter actually worked with him). In his famous textbook The Cell, Wilson linked Boveri and Sutton together by the Boveri-Sutton theory. Mayr remarks that the theory was hotly contested by some famous geneticists: William Bateson, Wilhelm Johannsen, Richard Goldschmidt and T.H. Morgan, all of a rather dogmatic turn of mind. Eventually complete proof came from chromosome maps – in Morgan's own lab! [12] Wilhelm Roux (June 9, 1850–September 15, 1924) was a German zoologist and experimental embryologist. ... Edmund Beecher Wilson (1856 - 1939) was an American geneticist and zoologist. ... Walter Stanborough Sutton (April 5, 1877 - November 10, 1916) was an American biologist whose most significant contribution to present-day biology was his theory that the Mendelian laws of inheritance could be applied to chromosomes at the cellular level. ... This article needs cleanup. ... William Bateson. ... Wilhelm Ludvig Johannsen (February 3, 1857 - November 11, 1927) was a Danish botanist. ... Richard Benedict Goldschmidt (April 12, 1878 – April 24, 1958) was a German-born American geneticist. ... Thomas Hunt Morgan in 1891. ...


Chromosomes in eukaryotes

Eukaryotes (cells with nuclei such as plants, yeast, and animals) possess multiple large linear chromosomes contained in the cell's nucleus. Each chromosome has one centromere, with one or two arms projecting from the centromere, although under most circumstances these arms are not visible as such. In addition most eukaryotes have a small circular mitochondrial genome, and some eukaryotes may have additional small circular or linear cytoplasmic chromosomes. Image File history File links Mergefrom. ... Eukaryotic chromosome fine structure refers to the structure of sequences for eukaryotic chromosomes. ... Kingdoms Eukaryotes are organisms with complex cells, in which the genetic material is organized into membrane-bound nuclei. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... Chromosome. ... In cell biology, a mitochondrion is an organelle found in the cells of most eukaryotes. ... Schematic showing the cytoplasm, with major components of a typical animal cell. ...


In the nuclear chromosomes of eukaryotes, the uncondensed DNA exists in a semi-ordered structure, where it is wrapped around histones (structural proteins), forming a composite material called chromatin. Kingdoms Animalia - Animals Fungi Plantae - Plants Chromalveolata Protista Alternative phylogeny Unikonta Opisthokonta Metazoa Choanozoa Eumycota Amoebozoa Bikonta Apusozoa Cabozoa Rhizaria Excavata Corticata Archaeplastida Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms whose cells are organized into complex structures by internal membranes and a cytoskeleton. ... Schematic representation of the assembly of the core histones into the nucleosome. ... A representation of the 3D structure of myoglobin showing coloured alpha helices. ... Chromatin is the complex of DNA and protein found inside the nuclei of eukaryotic cells. ...


Chromatin

Main article: Chromatin
Fig. 2: The major structures in DNA compaction; DNA, the nucleosome, the 10nm "beads-on-a-string" fibre, the 30nm fibre and the metaphase chromosome.
Fig. 2: The major structures in DNA compaction; DNA, the nucleosome, the 10nm "beads-on-a-string" fibre, the 30nm fibre and the metaphase chromosome.

Chromatin is the complex of DNA and protein found in the eukaryotic nucleus which packages chromosomes. The structure of chromatin varies significantly between different stages of the cell cycle, according to the requirements of the DNA. Chromatin is the complex of DNA and protein found inside the nuclei of eukaryotic cells. ... Image File history File links Download high-resolution version (1312x432, 203 KB) By Richard Wheeler (Zephyris) 2005; The major chromatin structures. ... Image File history File links Download high-resolution version (1312x432, 203 KB) By Richard Wheeler (Zephyris) 2005; The major chromatin structures. ... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... A nucleosome is a unit made of DNA and histones. ... An image of a newt lung cell stained with fluorescent dyes during metaphase. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Chromalveolata Protista Alternative phylogeny Unikonta Opisthokonta Metazoa Choanozoa Eumycota Amoebozoa Bikonta Apusozoa Cabozoa Rhizaria Excavata Corticata Archaeplastida Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms whose cells are organized into complex structures by internal membranes and a cytoskeleton. ... The cell cycle, or cell-division cycle, is the series of events that take place in a eukaryotic cell leading to its replication. ...


Interphase chromatin

During interphase (the period of the cell cycle where the cell is not dividing) two types of chromatin can be distinguished: Interphase is a phase of the cell cycle. ... The cell cycle, or cell-division cycle, is the series of events that take place in a eukaryotic cell leading to its replication. ... Chromatin is the complex of DNA and protein found inside the nuclei of eukaryotic cells. ...

  • Euchromatin, which consists of DNA that is active, e.g., expressed as protein.
  • Heterochromatin, which consists of mostly inactive DNA. It seems to serve structural purposes during the chromosomal stages. Heterochromatin can be further distinguished into two types:
    • Constitutive heterochromatin, which is never expressed. It is located around the centromere and usually contains repetitive sequences.
    • Facultative heterochromatin, which is sometimes expressed.

Individual chromosomes cannot be distinguished at this stage - they appear in the nucleus as a homogeneous tangled mix of DNA and protein. Euchromatin is a lightly packed form of chromatin that is rich in gene concentration, and is often (but not always) under active transcription. ... For differently-colored eyes, see Heterochromia. ... In the study of DNA sequences, one can distinguish two main types of repeated sequence: Tandem repeats: Satellite DNA, Minisatellite, Microsatellite; Interspersed repeats: SINEs (Short INterspersed Elements), LINEs (Long INterspersed Elements). ...


Metaphase chromatin and division

See also: mitosis and meiosis
Human chromosomes during metaphase.
Human chromosomes during metaphase.

In the early stages of mitosis or meiosis (cell division), the chromatin strands become more and more condensed. They cease to function as accessible genetic material (transcription stops) and become a compact transportable form. This compact form makes the individual chromosomes visible, and they form the classic four arm structure, a pair of sister chromatids attached to each other at the centromere. The shorter arms are called p arms (from the French petit, small) and the longer arms are called q arms (q follows p in the Latin alphabet). This is the only natural context in which individual chromosomes are visible with an optical microscope. Mitosis divides genetic information during cell division. ... For the figure of speech, see meiosis (figure of speech). ... Image File history File linksMetadata HumanChromosomesChromomycinA3. ... Image File history File linksMetadata HumanChromosomesChromomycinA3. ... An image of a newt lung cell stained with fluorescent dyes during metaphase. ... A micrograph of ongoing gene transcription of ribosomal RNA illustrating the growing primary transcripts. ... A chromatid forms one part of a chromosome after it has coalesced for the process of mitosis or meiosis. ... Chromosome. ... A microscope (Greek: (micron) = small + (skopein) = to look at) is an instrument for viewing objects that are too small to be seen by the naked or unaided eye. ...


During divisions long microtubules attach to the centromere and the two opposite ends of the cell. The microtubules then pull the chromatids apart, so that each daughter cell inherits one set of chromatids. Once the cells have divided, the chromatids are uncoiled and can function again as chromatin. In spite of their appearance, chromosomes are structurally highly condensed which enables these giant DNA structures to be contained within a cell nucleus (Fig. 2). Microtubules are one of the components of the cytoskeleton. ...


The self assembled microtubules form the spindle, which attaches to chromosomes at specialized structures called kinetochores, one of which is present on each sister chromatid. A special DNA base sequence in the region of the kinetochores provides, along with special proteins, longer-lasting attachment in this region. A chromatid forms one part of a chromosome after it has coalesced for the process of mitosis or meiosis. ...


Chromosomes in prokaryotes

The prokaryotes - bacteria and archaea - typically have a single circular chromosome, but many variations do exist.[13] Most bacteria have a single circular chromosome that can range in size from only 160,000 base pairs in the endosymbiotic bacteria Candidatus Carsonella ruddii,[14] to 12,200,000 base pairs in the soil-dwelling bacteria Sorangium cellulosum.[15] Spirochaetes of the genus Borrelia are a notable exception to this arrangement, with bacteria such as Borrelia burgdorferi, the cause of Lyme disease, containing a single linear chromosome.[16] Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Phyla Crenarchaeota Euryarchaeota Korarchaeota Nanoarchaeota ARMAN The Archaea (pronounced ) are a group of prokaryotic and single-celled microorganisms. ... Base pairs, of a DNA molecule. ... An endosymbiont is any organism that lives within the body or cells of another organism, i. ... Binomial name Candidatus Carsonella ruddii Synonyms Carsonella ruddii Candidatus Carsonella ruddii is an endosymbiotic Gamma Proteobacteria; it has the smallest genome of any characterised bacteria. ... Sorangium cellulosum is a soil-dwelling Gram-negative bacteria of the group myxobacteria. ... Families Spirochaetaceae Brachyspiraceae    Brachyspira    Serpulina Leptospiraceae    Leptospira    Leptonema Spirochaetes is a phylum of distinctive Gram-negative bacteria, which have long, helically coiled cells. ... For other uses, see Genus (disambiguation). ... Binomial name Borrelia burgdorferi Johnson RC et al 1984 Borrelia burgdorferi is a spirochete bacteria and the causative agent of Lyme disease. ... Lyme disease, or borreliosis, is an emerging infectious disease caused by at least three species of bacteria from the genus Borrelia. ...


Structure in sequences

Prokaryotes chromosomes have less sequence-based structure than eukaryotes. Bacteria typically have a single point (the origin of replication) from which replication starts, while some archaea contain multiple replication origins.[17] The genes in prokaryotes are often organised in operons, and do not contain introns, unlike eukaryotes. The origin of replication (also called the replication origin) is a particular DNA sequence at which DNA replication is initiated. ... An operon is a group of genes including an operator, a common promoter, and one or more structural genes that are controlled as a unit to produce messenger RNA (mRNA). ... Diagram of the location of introns and exons within a gene. ...


DNA packaging

Prokaryotes do not possess nuclei, instead their DNA is organized into a structure called the nucleoid.[18] The nucleoid is a distinct structure and occupies a defined region of the bacterial cell. This structure is however dynamic and is maintained and remodeled by the actions of a range of histone-like proteins, which associate with the bacterial chromosome.[19] In archaea, the DNA in chromosomes is even more organized, with the DNA packaged within structures similar to eukaryotic nucleosomes.[20][21] Prokaryotic bacteria cell structure Prokaryotes (IPA: //) are a group of organisms that lack a cell nucleus (= karyon), or any other membrane-bound organelles. ... It has been suggested that Genophore be merged into this article or section. ... Phyla Crenarchaeota Euryarchaeota Korarchaeota Nanoarchaeota ARMAN The Archaea (pronounced ) are a group of prokaryotic and single-celled microorganisms. ...


Bacterial chromosomes tend to be tethered to the plasma membrane of the bacteria. In molecular biology application, this allows for its isolation from plasmid DNA by centrifugation of lysed bacteria and pelleting of the membranes (and the attached DNA). Drawing of a cell membrane A component of every biological cell, the cell membrane (or plasma membrane) is a thin and structured bilayer of phospholipid and protein molecules that envelopes the cell. ...


Prokaryotic chromosomes and plasmids are, like eukaryotic DNA, generally supercoiled. The DNA must first be released into its relaxed state for access for transcription, regulation, and replication. The mechanical properties of DNA are closly related to its molecular structure and the relative weakness of the hydrogen bonds and electronic interactions that hold strands of DNA together compared to the strength of the bonds within each strand. ... A micrograph of ongoing gene transcription of ribosomal RNA illustrating the growing primary transcripts. ... DNA replication. ...


Number of chromosomes in various organisms

Aulacantha has the largest diploid number of chromosomes This page lists the numbers of Chromosomes in various plants, animals, protists, and other living organisms, given as the diploid number (2n) // African Wild Dog 78 Alfalfa 16 Algae 148 Amoeba 13 American Badger 32 American Marten 38 American Mink 30 Aulacantha...

Eukaryotes

These tables give the total number of chromosomes (including sex chromosomes) in a cell nucleus. For example, human cells are diploid and have 22 different types of autosomes, each present as two copies, and two sex chromosomes. This gives 46 chromosomes in total. Other organisms have more than two copies of their chromosomes, such as Bread wheat which is hexaploid and has six copies of 6 different chromosomes - 42 chromosomes in total. Diploid (meaning double in Greek) cells have two copies (homologs) of each chromosome (both sex- and non-sex determining chromosomes), usually one from the mother and one from the father. ... An autosome is a non-sex chromosome. ... A sex-determination system is a biological system that determines the development of sexual characteristics in an organism. ... Binomial name Triticum aestivum L. Common wheat (also known as bread wheat) is by far the most important wheat species in cultivation today. ...

Chromosome numbers in some plants
Plant Species #
Arabidopsis thaliana (diploid)[22] 10
Rye (diploid)[23] 14
Maize (diploid)[24] 20
Einkorn wheat (diploid)[25] 14
Durum wheat (tetraploid)[25] 28
Bread wheat (hexaploid)[25] 42
Potato (tetraploid)[26] 48
Cultivated tobacco (diploid)[27] 48
Adder's Tongue Fern (diploid)[28] approx 1,440
Chromosome numbers (2n) in some animals
Species # Species #
Common fruit fly 8 Guinea Pig[29] 64
Dove[citation needed] 16 Garden snail[30] 54
Earthworm Octodrilus complanatus[31] 36 Tibetan fox 36
Domestic cat[32] 38 Domestic pig 38
Lab mouse 40 Lab rat 42
Rabbit[citation needed] 44 Syrian hamster 44
Hare[citation needed] 46 Human[33] 46
Gorillas, Chimpanzees[33] 48 Domestic sheep 54
Elephants[34] 56 Cow 60
Donkey 62 Horse 64
Dog[35] 78 Kingfisher[36] 132
Goldfish[37] 100-104 Silkworm[38] 56
Chromosome numbers in other organisms
Species Large
Chromosomes
Intermediate
Chromosomes
Small
Chromosomes
Trypanosoma brucei 11 6 ~100
Chicken[39] 8 2 sex chromosomes 60

Normal members of a particular eukaryotic species all have the same number of nuclear chromosomes (see the table). Other eukaryotic chromosomes, i.e., mitochondrial and plasmid-like small chromosomes, are much more variable in number, and there may be thousands of copies per cell. Binomial name Arabidopsis thaliana (L.) Heynh. ... Binomial name Secale cereale M.Bieb. ... This article is about the maize plant. ... Binomial name Triticum boeoticum Boss. ... Durum wheat (T. turgidum durum) is the only tetraploid species of wheat widely cultivated today. ... Binomial name Triticum aestivum L. Common wheat (also known as bread wheat) is by far the most important wheat species in cultivation today. ... For other uses, see Potato (disambiguation). ... Species Ophioglossum azoricum Ophioglossum engelmanii Ophioglossum lusitanicum Ophioglossum pycnosticum Ophioglossum vulgatum Adders-tongues are plants of the genus Ophioglossum, which means snake-tongue. Ophioglossum is in the family Ophioglossaceae, in the order Ophioglossales, a small group of vascular plants. ... Binomial name Meigen, 1830[1] Drosophila melanogaster (from the Greek for black-bellied dew-lover) is a two-winged insect that belongs to the Diptera, the order of the flies. ... For other uses, see Guinea pig (disambiguation). ... Subfamilies see article text Feral Rock Pigeon beside Weiming Lake, Peking University Dove redirects here. ... Binomial name Helix aspersa (Müller, 1774) The brown garden snail (Helix aspersa) (syn. ... For the LPG album, see The Earthworm (album). ... Tibetan Fox (Vulpes ferrilata) Lives at a high plateau of Tibet, bordering on China and India. ... Trinomial name Felis silvestris catus Schreber, 1775 For alternative meanings see cat (disambiguation). ... Trinomial name Sus scrofa domestica Linnaeus, 1758 Synonyms Sus domestica The domestic pig (or in some areas hog) is normally given the scientific name Sus scrofa domestica, though some taxonomists use the term , reserving for the wild boar. ... Binomial name Mus musculus Linnaeus, 1758 Mus musculus is the house mouse. ... Binomial name Mus musculus Linnaeus, 1758 Mus musculus is the house mouse. ... For other uses, see Rabbit (disambiguation). ... Binomial name Waterhouse, 1839 The Syrian Hamster or Golden Hamster, Mesocricetus auratus, is the best known member of the rodent subfamily Cricetinae, the hamsters. ... For other uses, see Hare (disambiguation). ... This article is about modern humans. ... For other uses, see Gorilla (disambiguation). ... Type species Simia troglodytes Blumenbach, 1775 distribution of Species Pan troglodytes Pan paniscus Chimpanzee, often shortened to chimp, is the common name for the two extant species of apes in the genus Pan. ... Sheep redirects here. ... Genera and Species Loxodonta Loxodonta cyclotis Loxodonta africana Elephas Elephas maximus Elephas antiquus † Elephas beyeri † Elephas celebensis † Elephas cypriotes † Elephas ekorensis † Elephas falconeri † Elephas iolensis † Elephas planifrons † Elephas platycephalus † Elephas recki † Stegodon † Mammuthus † Elephantidae (the elephants) is a family of pachyderm, and the only remaining family in the order Proboscidea... For general information about the genus, including other species of cattle, see Bos. ... Binomial name Linnaeus, 1758 For other uses, see Donkey (disambiguation). ... Binomial name Equus caballus Linnaeus, 1758 The horse (Equus caballus, sometimes seen as a subspecies of the Wild Horse, Equus ferus caballus) is a large odd-toed ungulate mammal, one of ten modern species of the genus Equus. ... Trinomial name Canis lupus familiaris The dog (Canis lupus familiaris) is a domestic subspecies of the wolf, a mammal of the Canidae family of the order Carnivora. ... Families Alcedinidae Halcyonidae Cerylidae Kingfishers are birds of the three families Alcedinidae (river kingfishers), Halcyonidae (tree kingfishers), and Cerylidae (water kingfishers). ... For the snack marketed by Pepperidge Farm, see Goldfish (snack) Trinomial name Carassius auratus auratus (Linnaeus, 1758) The goldfish, Carassius auratus, was one of the earliest fish to be domesticated, and is still one of the most commonly kept aquarium fish and water garden fish. ... Binomial name Bombyx mori Linnaeus, 1758 “Silkworm” redirects here. ... Trypanosoma brucei is a species of parasitic protozoan trypanosomes. ... This article or section does not adequately cite its references or sources. ... For other uses, see Species (disambiguation). ...

The 24 human chromosome territories during prometaphase in fibroblast cells.
The 24 human chromosome territories during prometaphase in fibroblast cells.

Asexually reproducing species have one set of chromosomes, which is the same in all body cells. Image File history File linksMetadata Download high-resolution version (439x612, 117 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Cell nucleus Chromosome Metadata This file contains additional information, probably added from the digital camera or scanner used... Image File history File linksMetadata Download high-resolution version (439x612, 117 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Cell nucleus Chromosome Metadata This file contains additional information, probably added from the digital camera or scanner used... NIH/3T3 Fibroblasts A fibroblast is a type of cell that synthesizes and maintains the extracellular matrix of many animal tissues. ... It has been suggested that Parthenogenesis be merged into this article or section. ...


Sexually reproducing species have somatic cells (body cells), which are diploid [2n] having two sets of chromosomes, one from the mother and one from the father. Gametes, reproductive cells, are haploid [n]: they have one set of chromosomes. Gametes are produced by meiosis of a diploid germ line cell. During meiosis, the matching chromosomes of father and mother can exchange small parts of themselves (crossover), and thus create new chromosomes that are not inherited solely from either parent. When a male and a female gamete merge (fertilization), a new diploid organism is formed. Sexual reproduction is a union that results in increasing genetic diversity of the offspring. ... This article does not cite any references or sources. ... Ploidy is the number of homologous sets of chromosomes in a biological cell. ... A gamete (from Ancient Greek γαμετης; translated gamete = wife, gametes = husband) is a cell that fuses with another gamete during fertilization (conception) in organisms that reproduce sexually. ... Ploidy is the number of homologous sets of chromosomes in a biological cell. ... For the figure of speech, see meiosis (figure of speech). ... Germline is a word used in biology and genetics. ... Thomas Hunt Morgans illustration of crossing over (1916) Homologous Recombination is the process by which two chromosomes, paired up during prophase I of meiosis, exchange some distal portion of their DNA. Crossover occurs when two chromosomes, normally two homologous instances of the same chromosome, break and then reconnect but... Categories: Biology stubs ...


Some animal and plant species are polyploid [Xn]: they have more than two sets of homologous chromosomes. Agriculturally important plants such as tobacco or wheat are often polyploid compared to their ancestral species. Wheat has a haploid number of seven chromosomes, still seen in some cultivars as well as the wild progenitors. The more common pasta and bread wheats are polyploid, having 28 (tetraploid) and 42 (hexaploid) chromosomes compared to the 14 (diploid) chromosomes in the wild wheat.[40] Ploidy is the number of homologous sets of chromosomes in a biological cell. ... Homologous chromosomes are chromosomes in a biological cell that pair (synapse) during meiosis, or alternatively, non-identical chromosomes that contain information for the same biological features and contain the same genes at the same loci but possibly different genetic information, called alleles, at those genes. ... Shredded tobacco leaf for pipe smoking Tobacco can also be pressed into plugs and sliced into flakes Tobacco is an agricultural product processed from the fresh leaves of plants in the genus Nicotiana. ... Species T. aestivum T. boeoticum T. dicoccoides T. dicoccon T. durum T. monococcum T. spelta T. sphaerococcum T. timopheevii References:   ITIS 42236 2002-09-22 Wheat Wheat For the indie rock group, see Wheat (band). ... This Osteospermum Pink Whirls is a successful cultivar. ... Percentages are relative to US recommendations for adults. ... For other uses, see Bread (disambiguation). ...

Prokaryotes

Prokaryote species generally have one copy of each major chromosome, but most cells can easily survive with multiple copies.[41] For example, Buchnera, a symbiont of aphids has multiple copies of its chromosome, ranging from 10–400 copies per cell.[42] However, in some large bacteria, such as Epulopiscium fishelsoni up to 100,000 copies of the chromosome can be present.[43] Plasmids and plasmid-like small chromosomes are, like in eukaryotes, very variable in copy number. The number of plasmids in the cell is almost entirely determined by the rate of division of the plasmid - fast division causes high copy number, and vice versa. Prokaryotic bacteria cell structure Prokaryotes (IPA: //) are a group of organisms that lack a cell nucleus (= karyon), or any other membrane-bound organelles. ... For other uses, see Species (disambiguation). ... Bruchnera aphidicola, a member of the Proteobacteria, is the primary symbiont of A. psium. ... For other uses, see Symbiosis (disambiguation). ... Families There are 10 families: Anoeciidae Aphididae Drepanosiphidae Greenideidae Hormaphididae Lachnidae Mindaridae Pemphigidae Phloeomyzidae Thelaxidae Aphids, also known as greenfly or plant lice, are minute plant-feeding insects. ... Binomial name Epulopiscium fischelsoni Schulz , 1999 Epulopiscium fishelsoni (guest at a fishs banquet) is a gram-positive bacterium that has a symbiotic relationship with the surgeonfish. ...

Karyotype

Main article: Karyotype
Figure 3: Karyogram of a human male
Figure 3: Karyogram of a human male

In general, the karyotype is the characteristic chromosome complement of a eukaryote species.[44] The preparation and study of karyotypes is part of cytogenetics. Karyogram of human male using Giemsa staining. ... Image File history File links NHGRI_human_male_karyotype. ... Image File history File links NHGRI_human_male_karyotype. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Chromalveolata Protista Alternative phylogeny Unikonta Opisthokonta Metazoa Choanozoa Eumycota Amoebozoa Bikonta Apusozoa Cabozoa Rhizaria Excavata Corticata Archaeplastida Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms whose cells are organized into complex structures by internal membranes and a cytoskeleton. ... For other uses, see Species (disambiguation). ... A metaphase cell positive for the bcr/abl rearrangement using FISH Cytogenetics is the study of the structure of chromosome material. ...


Although the replication and transcription of DNA is highly standardized in eukaryotes, the same cannot be said for their karotypes, which are often highly variable. There may be variation between species in chromosome number and in detailed organization. In some cases there is significant variation within species. Often there is variation 1. between the two sexes. 2. between the germ-line and soma (between gametes and the rest of the body). 3. between members of a population, due to balanced genetic polymorphism. 4. geographical variation between races. 5. mosaics or otherwise abnormal individuals. Finally, variation in karyotype may occur during development from the fertilised egg. Replication may mean: In biology: Self-replication, when a molecule (or any other pattern) makes a copy of itself DNA replication, the act of copying the genetic material of a cell (DNA) to a daughter cell Semiconservative replication, mechanism of DNA replication Other: replication (computer science), the provision of redundant... Look up Transcription in Wiktionary, the free dictionary. ... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... Kingdoms Eukaryotes are organisms with complex cells, in which the genetic material is organized into membrane-bound nuclei. ... Germline is a word used in biology and genetics. ... This article is about the Vedic plant and ritual. ... Gametes (in Greek: γαμέτες) —also known as sex cells, germ cells, or spores—are the specialized cells that come together during fertilization (conception) in organisms that reproduce sexually. ... In biology, polymorphism can be defined as the occurrence in the same habitat of two or more forms of a trait in such frequencies that the rarer cannot be maintained by recurrent mutation alone. ... Allopatric speciation, also known as geographic speciation, occurs when populations physically isolated by an extrinsic barrier evolve intrinsic (genetic) reproductive isolation such that if the barrier between the populations breaks down, individuals of the two populations can no longer interbreed. ... For other uses, see Race. ... In medicine (genetics), a mosaic or mosaicism denotes the presence of two populations of cells with different genotypes in one patient, where usually one of the two is affected by a genetic disorder. ...


The technique of determining the karyotype is usually called karyotyping. Cells can be locked part-way through division (in metaphase) in vitro (in a reaction vial) with colchicine. These cells are then stained, photographed and arranged into a karyogram, with the set of chromosomes arranged, autosomes in order of length, and sex chromosomes (here XY) at the end: Fig. 3. In vitro (Latin: within the glass) refers to the technique of performing a given experiment in a test tube, or, generally, in a controlled environment outside a living organism. ... Colchicine is a highly deadly poisonous alkaloid, originally extracted from plants of the genus Colchicum (Autumn crocus, also known as the Meadow saffron). Originally used to treat rheumatic complaints and especially gout, it was also prescribed for its cathartic and emetic effects. ...


Like many sexually reproducing species, humans have special gonosomes (sex chromosomes, in contrast to autosomes). These are XX in females and XY in males. Drosophila sex-chromosomes The XY sex-determination system is the sex-determination system found in humans, most other mammals, some insects (Drosophila) and some plants (Ginkgo). ... An autosome is a non-sex chromosome. ...

Historical note

Investigation into the human karyotype took many years to settle the most basic question: how many chromosomes does a normal diploid human cell contain? In 1912, Hans von Winiwarter reported 47 chromosomes in spermatogonia and 48 in oogonia, concluding an XX/XO sex determination mechanism.[45] Painter in 1922 was not certain whether the diploid number of man was 46 or 48, at first favouring 46.[46] He revised his opinion later from 46 to 48, and he correctly insisted on man having an XX/XY system.[47] Considering their techniques, these results were quite remarkable. Diploid (meaning double in Greek) cells have two copies (homologs) of each chromosome (both sex- and non-sex determining chromosomes), usually one from the mother and one from the father. ... The introduction of this article does not provide enough context for readers unfamiliar with the subject. ... A cell that arises from a primordial germ cell and differentiates into an oocyte in the ovary. ... A sex-determination system is a biological system that determines the development of sexual characteristics in an organism. ... This article needs cleanup. ... Drosophila sex-chromosomes The XY sex-determination system is the sex-determination system found in humans, most other mammals, some insects (Drosophila) and some plants (Ginkgo). ...


New techniques were needed to definitively solve the problem:

1. Using cells in culture
2. Pretreating cells in a hypotonic solution, which swells them and spreads the chromosomes
3. Arresting mitosis in metaphase by a solution of colchicine
4. Squashing the preparation on the slide forcing the chromosomes into a single plane
5. Cutting up a photomicrograph and arranging the result into an indisputable karyogram.

It took until the mid 1950s until it became generally accepted that the human karyotype included only 46 chromosomes.[48][49] Rather interestingly, chimpanzees (our closest living relatives) have 48 chromosomes. Tonicity is a measure of effective osmolarity or effective osmolality. ... Mitosis divides genetic information during cell division. ... An image of a newt lung cell stained with fluorescent dyes during metaphase. ... Colchicine is a highly deadly poisonous alkaloid, originally extracted from plants of the genus Colchicum (Autumn crocus, also known as the Meadow saffron). Originally used to treat rheumatic complaints and especially gout, it was also prescribed for its cathartic and emetic effects. ...

Chromosomal aberrations

The three major single chromosome mutations; deletion (1), duplication (2) and inversion (3).
The three major single chromosome mutations; deletion (1), duplication (2) and inversion (3).
The two major two-chromosome mutations; insertion (1) and translocation (2).
The two major two-chromosome mutations; insertion (1) and translocation (2).
In Down syndrome, there are three copies of chromosome 21
In Down syndrome, there are three copies of chromosome 21

Chromosomal aberrations are disruptions in the normal chromosomal content of a cell, and are a major cause of genetic conditions in humans, such as Down syndrome. Some chromosome abnormalities do not cause disease in carriers, such as translocations, or chromosomal inversions, although they may lead to a higher chance of having a child with a chromosome disorder. Abnormal numbers of chromosomes or chromosome sets, aneuploidy, may be lethal or give rise to genetic disorders. Genetic counseling is offered for families that may carry a chromosome rearrangement. A chromosome abnormality reflects an abnormality of chromosome number or structure. ... Aneuploidy is a change in the number of chromosomes that can lead to a chromosomal disorder. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Image File history File links Size of this preview: 431 × 599 pixel Image in higher resolution (616 × 856 pixel, file size: 19 KB, MIME type: image/png) By Richard Wheeler (Zephyris) 2007. ... Image File history File links Size of this preview: 431 × 599 pixel Image in higher resolution (616 × 856 pixel, file size: 19 KB, MIME type: image/png) By Richard Wheeler (Zephyris) 2007. ... Image File history File links The human chromosome 21 is affected in Down syndrome. ... Image File history File links The human chromosome 21 is affected in Down syndrome. ... Chromosomal translocation of the 4th and 20th chromosome. ... An inversion is a chromosome rearrangement in which a segment of a chromosome is reversed end to end. ... Aneuploidy is a change in the number of chromosomes that can lead to a chromosomal disorder. ... Genetic counseling is the process by which patients or relatives, at risk of an inherited disorder, are advised of the consequences and nature of the disorder, the probability of developing or transmitting it, and the options open to them in management and family planning in order to prevent, avoid or...


The gain or loss of chromosome material can lead to a variety of genetic disorders. Human examples include: A genetic disorder, or genetic disease is a disease caused, at least in part, by the genes of the person with the disease. ...

  • Cri du chat, which is caused by the deletion of part of the short arm of chromosome 5. "Cri du chat" means "cry of the cat" in French, and the condition was so-named because affected babies make high-pitched cries that sound like a cat. Affected individuals have wide-set eyes, a small head and jaw and are moderately to severely mentally retarded and very short.
  • Wolf-Hirschhorn syndrome, which is caused by partial deletion of the short arm of chromosome 4. It is characterized by severe growth retardation and severe to profound mental retardation.
  • Down's syndrome, usually is caused by an extra copy of chromosome 21 (trisomy 21). Characteristics include decreased muscle tone, stockier build, asymmetrical skull, slanting eyes and mild to moderate mental retardation.[50]
  • Edwards syndrome, which is the second most common trisomy after Down syndrome. It is a trisomy of chromosome 18. Symptoms include mental and motor retardation and numerous congenital anomalies causing serious health problems. Ninety percent die in infancy; however, those who live past their first birthday usually are quite healthy thereafter. They have a characteristic hand appearance with clenched hands and overlapping fingers.
  • Patau Syndrome, also called D-Syndrome or trisomy-13. Symptoms are somewhat similar to those of trisomy-18, but they do not have the characteristic hand shape.
  • Idic15, abbreviation for Isodicentric 15 on chromosome 15; also called the following names due to various researches, but they all mean the same; IDIC(15), Inverted dupliction 15, extra Marker, Inv dup 15, partial tetrasomy 15
  • Jacobsen syndrome, also called the terminal 11q deletion disorder.[1] This is a very rare disorder. Those affected have normal intelligence or mild mental retardation, with poor expressive language skills. Most have a bleeding disorder called Paris-Trousseau syndrome.
  • Klinefelter's syndrome (XXY). Men with Klinefelter syndrome are usually sterile, and tend to have longer arms and legs and to be taller than their peers. Boys with the syndrome are often shy and quiet, and have a higher incidence of speech delay and dyslexia. During puberty, without testosterone treatment, some of them may develop gynecomastia.
  • Turner syndrome (X instead of XX or XY). In Turner syndrome, female sexual characteristics are present but underdeveloped. People with Turner syndrome often have a short stature, low hairline, abnormal eye features and bone development and a "caved-in" appearance to the chest.
  • XYY syndrome. XYY boys are usually taller than their siblings. Like XXY boys and XXX girls, they are somewhat more likely to have learning difficulties.
  • Triple-X syndrome (XXX). XXX girls tend to be tall and thin. They have a higher incidence of dyslexia.
  • Small supernumerary marker chromosome. This means there is an extra, abnormal chromosome. Features depend on the origin of the extra genetic material. Cat-eye syndrome and isodicentric chromosome 15 syndrome (or Idic15) are both caused by a supernumerary marker chromosome, as is Pallister-Killian syndrome.

Chromosomal mutations produce changes in whole chromosomes (more than one gene) or in the number of chromosomes present. Cri du Chat syndrome or Cri-du-Chat syndrome (French for Cry or call of the cat referring to the specific cry of the child), also called deletion 5p syndrome, 5p minus or Lejeune’s syndrome, is a rare genetic disorder due to a missing portion of chromosome 5. ... A genetic deletion is a genetic aberration in which part of a chromosome is missing. ... Wolf-Hirschhorn syndrome, also known as deletion 4p and 4p- syndrome was first described in 1961 by U. Wolf and K. Hirschhorn and their co-workers. ... A child with Down syndrome Down syndrome (also called Downs syndrome) encompasses a number of genetic disorders, of which trisomy 21 (a nondisjunction) is the most representative, causing highly variable degrees of learning difficulties and physical disabilities. ... A child with Down syndrome Down syndrome (also called Downs syndrome) encompasses a number of genetic disorders, of which trisomy 21 (a nondisjunction) is the most representative, causing highly variable degrees of learning difficulties and physical disabilities. ... ‹ The template below (Citations missing) is being considered for deletion. ... Patau syndrome, also known as trisomy 13, is a chromosomal abnormality, a syndrome in which a patient has an additional chromosome 13 due to a non-disjunction of chromosomes during meiosis. ... To meet Wikipedias quality standards, this article may require cleanup. ... Summary Jacobsen Syndrome, also known as 11q deletion, is a congenital disorder that occurs due to a partial deletion of the terminal band on chromosome 11. ... Not to be confused with XXX syndrome. ... This article is about developmental dyslexia. ... Gynecomastia, or gynaecomastia, pronounced is the development of abnormally large mammary glands in males resulting in breast enlargement, which can sometimes cause secretion of milk. ... Not to be confused with XXY syndrome. ... Triple X syndrome is a chromosomal aneuploid abnormality characterized by the presence of an extra X chromosome in each cell of a human female. ... Humans typically have 22 pairs autosomal chromosomes in our cells, and a pair of sex chromosomes. ... Synonyms CES Schmid-Fraccaro Syndrome Chromosome 22, Partial Tetrasomy (22pter-22q11) Chromosome 22, Partial Trisomy (22pter-22q11) Chromosome 22, Inverted Duplication (22pter-22q11) Cat-eye syndrome is a rare chromosomal disorder that may be evident at birth. ... To meet Wikipedias quality standards, this article may require cleanup. ... Pallister-Killian syndrome (also tetrasomy 12p mosaicism or Pallister mosaic aneuploidy syndrome) is an extremely rare genetic disorder occurring in humans. ...

  • Deletion - loss of part of a chromosome
  • Duplication - extra copies of a part of a chromosome
  • Inversion - reverse the direction of a part of a chromosome
  • Translocation - part of a chromosome breaks off and attaches to another chromosome

Most mutations are neutral - have little or no effect


A detailed graphical display of all human chromosomes and the diseases annotated at the correct spot may be found at [2].

Human chromosomes

Human cells have 23 pairs of large linear nuclear chromosomes, giving a total of 46 per cell. In addition to these, human cells have many hundreds of copies of the mitochondrial genome. Sequencing of the human genome has provided a great deal of information about each of the chromosomes. Below is a table compiling statistics for the chromosomes, based on the Sanger Institute's human genome information in the Vertebrate Genome Annotation (VEGA) database.[51] Number of genes is an estimate as it is in part based on gene predictions. Total chromosome length is an estimate as well, based on the estimated size of unsequenced heterochromatin regions. The mitochondrial genome is the genetic material of the mitochondria. ... The term DNA sequencing encompasses biochemical methods for determining the order of the nucleotide bases, adenine, guanine, cytosine, and thymine, in a DNA oligonucleotide. ... The Wellcome Trust Sanger Institute (formally the Sanger Centre) is a genome research centre in Cambridgeshire, England. ... 7Gene finding typically refers to the area of computational biology that is concerned with algorithmically identifying stretches of sequence, usually genomic DNA, that are biologically functional. ... For differently-colored eyes, see Heterochromia. ...

Chromosome Genes Total bases Sequenced bases[52]
1 3,148 247,200,000 224,999,719
2 902 242,750,000 237,712,649
3 1,436 199,450,000 194,704,827
4 453 191,260,000 187,297,063
5 609 180,840,000 177,702,766
6 1,585 170,900,000 167,273,992
7 1,824 158,820,000 154,952,424
8 781 146,270,000 142,612,826
9 1,229 140,440,000 120,312,298
10 1,312 135,370,000 131,624,737
11 405 134,450,000 131,130,853
12 1,330 132,290,000 130,303,534
13 623 114,130,000 95,559,980
14 886 106,360,000 88,290,585
15 676 100,340,000 81,341,915
16 898 88,820,000 78,884,754
17 1,367 78,650,000 77,800,220
18 365 76,120,000 74,656,155
19 1,553 63,810,000 55,785,651
20 816 62,440,000 59,505,254
21 446 46,940,000 34,171,998
22 595 49,530,000 34,893,953
X (sex chromosome) 1,093 154,910,000 151,058,754
Y (sex chromosome) 125 57,740,000 22,429,293

See also

External links

References

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  51. ^ http://vega.sanger.ac.uk/Homo_sapiens/index.html All data in this table was derived from this database, July 7 2007.
  52. ^ Sequenced percentages are based on fraction of euchromatin portion, as the Human Genome Project goals called for determination of only the euchromatic portion of the genome. Telomeres, centromeres, and other heterochromatic regions have been left undetermined, as have a small number of unclonable gaps. See http://www.ncbi.nlm.nih.gov/genome/seq/ for more information on the Human Genome Project.

A nucleosome is a unit made of DNA and histones. ... A telomere is a region of highly repetitive DNA at the end of a linear chromosome that functions as a disposable buffer. ... A chromatid forms one part of a chromosome after it has coalesced for the process of mitosis or meiosis. ...


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Chromosome fusion (913 words)
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