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60-436: Haplo may refer to: Haplogroup Fish [ edit ] Haplo (fish) , a common name for many fish classified in the tribe Haplochromini Giant haplo Bluelip haplo Ncheni haplo See also [ edit ] Ploidy The Death Gate Cycle Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with

120-459: A cell nucleus. Chromosomes in humans can be divided into two types: autosomes (body chromosome(s)) and allosome ( sex chromosome (s)). Certain genetic traits are linked to a person's sex and are passed on through the sex chromosomes. The autosomes contain the rest of the genetic hereditary information. All act in the same way during cell division. Human cells have 23 pairs of chromosomes (22 pairs of autosomes and one pair of sex chromosomes), giving

180-418: A crucial role in genetic diversity . If these structures are manipulated incorrectly, through processes known as chromosomal instability and translocation , the cell may undergo mitotic catastrophe . This will usually cause the cell to initiate apoptosis , leading to its own death , but the process is occasionally hampered by cell mutations that result in the progression of cancer . The term 'chromosome'

240-650: A different genetic configuration , and Boveri was able to test and confirm this hypothesis. Aided by the rediscovery at the start of the 1900s of Gregor Mendel 's earlier experimental work, Boveri identified the connection between the rules of inheritance and the behaviour of the chromosomes. Two generations of American cytologists were influenced by Boveri: Edmund Beecher Wilson , Nettie Stevens , Walter Sutton and Theophilus Painter (Wilson, Stevens, and Painter actually worked with him). In his famous textbook, The Cell in Development and Heredity , Wilson linked together

300-495: A direct female line of descent. Mutations are changes in the nitrogen bases of the DNA sequence . Single changes from the original sequence are called single nucleotide polymorphisms (SNPs). Human Y chromosomes are male-specific sex chromosomes ; nearly all humans that possess a Y chromosome will be morphologically male. Although Y chromosomes are situated in the cell nucleus and paired with X chromosomes , they only recombine with

360-489: A higher chance of bearing a child with a chromosome disorder. Abnormal numbers of chromosomes or chromosome sets, called aneuploidy , may be lethal or may give rise to genetic disorders. Genetic counseling is offered for families that may carry a chromosome rearrangement. The gain or loss of DNA from chromosomes can lead to a variety of genetic disorders . Human examples include: Exposure of males to certain lifestyle, environmental and/or occupational hazards may increase

420-439: A more recent haplogroup (which is a subgroup or subclade ) of its own to which humans carrying only mutation A do not belong. Both mtDNA and Y chromosomes are grouped into lineages and haplogroups; these are often presented as tree-like diagrams. Human Y chromosome DNA (Y-DNA) haplogroups are named from A to T, and are further subdivided using numbers and lower case letters. Y chromosome haplogroup designations are established by

480-439: A non-colored state. Otto Bütschli was the first scientist to recognize the structures now known as chromosomes. In a series of experiments beginning in the mid-1880s, Theodor Boveri gave definitive contributions to elucidating that chromosomes are the vectors of heredity , with two notions that became known as 'chromosome continuity' and 'chromosome individuality'. Wilhelm Roux suggested that every chromosome carries

540-403: A preceding single haplogroup (or paragroup ). As such, any related group of haplogroups may be precisely modelled as a nested hierarchy , in which each set (haplogroup) is also a subset of a single broader set (as opposed, that is, to biparental models, such as human family trees). Haplogroups can be further divided into subclades. Haplogroups are normally identified by an initial letter of

600-481: A semi-ordered structure, where it is wrapped around histones (structural proteins), forming a composite material called chromatin. The packaging of DNA into nucleosomes causes a 10 nanometer fibre which may further condense up to 30 nm fibres Most of the euchromatin in interphase nuclei appears to be in the form of 30-nm fibers. Chromatin structure is the more decondensed state, i.e. the 10-nm conformation allows transcription. During interphase (the period of

660-436: A set of ten Y chromosomes (derived from ten different individuals) contains a mutation, A, but only five of these chromosomes contain a second mutation, B, then it must be the case that mutation B occurred after mutation A. Furthermore, all ten individuals who carry the chromosome with mutation A are the direct male line descendants of the same man who was the first person to carry this mutation. The first man to carry mutation B

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720-542: 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 . Number of genes

780-440: Is hexaploid , having six copies of seven different chromosome types for a total of 42 chromosomes. Normal members of a particular eukaryotic species all have the same number of nuclear chromosomes. 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. Asexually reproducing species have one set of chromosomes that are

840-413: 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. Based on the micrographic characteristics of size, position of the centromere and sometimes the presence of a chromosomal satellite , the human chromosomes are classified into the following groups: In general, the karyotype

900-408: Is contained in the chromosomes in the nucleus of the cell, but mtDNA is an exception. An individual inherits their cytoplasm and the organelles contained by that cytoplasm exclusively from the maternal ovum (egg cell); sperm only pass on the chromosomal DNA, all paternal mitochondria are digested in the oocyte . When a mutation arises in a mtDNA molecule, the mutation is therefore passed down in

960-622: Is duplicated ( S phase ), and the two copies are joined by a centromere —resulting in either an X-shaped structure if the centromere is located equatorially, or a two-armed structure if the centromere is located distally; the joined copies are called ' sister chromatids '. During metaphase , the duplicated structure (called a 'metaphase chromosome') is highly condensed and thus easiest to distinguish and study. In animal cells, chromosomes reach their highest compaction level in anaphase during chromosome segregation . Chromosomal recombination during meiosis and subsequent sexual reproduction plays

1020-605: Is organized into a structure called the nucleoid . 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. In archaea , the DNA in chromosomes is even more organized, with the DNA packaged within structures similar to eukaryotic nucleosomes. Certain bacteria also contain plasmids or other extrachromosomal DNA . These are circular structures in

1080-449: Is passed solely along the patrilineal line, from father to son, while mtDNA is passed down the matrilineal line, from mother to offspring of both sexes. Neither recombines , and thus Y-DNA and mtDNA change only by chance mutation at each generation with no intermixture between parents' genetic material. Mitochondria are small organelles that lie in the cytoplasm of eukaryotic cells , such as those of humans. Their primary function

1140-544: 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. The microtubules then pull the chromatids apart toward the centrosomes, so that each daughter cell inherits one set of chromatids. Once the cells have divided, the chromatids are uncoiled and DNA can again be transcribed. In spite of their appearance, chromosomes are structurally highly condensed, which enables these giant DNA structures to be contained within

1200-413: Is significant variation within species. Often there is: Also, variation in karyotype may occur during development from the fertilized egg. 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

1260-440: Is sometimes used in a wider sense to refer to the individualized portions of chromatin in cells, which may or may not be visible under light microscopy. In a narrower sense, 'chromosome' can be used to refer to the individualized portions of chromatin during cell division, which are visible under light microscopy due to high condensation. The word chromosome ( / ˈ k r oʊ m ə ˌ s oʊ m , - ˌ z oʊ m / ) comes from

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1320-425: Is the characteristic chromosome complement of a eukaryote species . The preparation and study of karyotypes is part of cytogenetics . Although the replication and transcription of DNA is highly standardized in eukaryotes, the same cannot be said for their karyotypes, which are often highly variable. There may be variation between species in chromosome number and in detailed organization. In some cases, there

1380-429: Is the only natural context in which individual chromosomes are visible with an optical microscope . Mitotic metaphase chromosomes are best described by a linearly organized longitudinally compressed array of consecutive chromatin loops. During mitosis, microtubules grow from centrosomes located at opposite ends of the cell and also attach to the centromere at specialized structures called kinetochores , one of which

1440-412: Is to provide energy to the cell. Mitochondria are thought to be reduced descendants of symbiotic bacteria that were once free living. One indication that mitochondria were once free living is that each contains a circular DNA , called mitochondrial DNA (mtDNA), whose structure is more similar to bacteria than eukaryotic organisms (see endosymbiotic theory ). The overwhelming majority of a human's DNA

1500-553: The Greek words χρῶμα ( chroma , "colour") and σῶμα ( soma , "body"), describing the strong staining produced by particular dyes . The term was coined by the German anatomist Heinrich Wilhelm Waldeyer , referring to the term ' chromatin ', which was introduced by Walther Flemming . Some of the early karyological terms have become outdated. For example, 'chromatin' (Flemming 1880) and 'chromosom' (Waldeyer 1888) both ascribe color to

1560-681: The Sami people . Here is a list of Y-chromosome and MtDNA geographic haplogroup assignment proposed by Bekada et al. 2013. According to SNPS haplogroups which are the age of the first extinction event tend to be around 45–50 kya. Haplogroups of the second extinction event seemed to diverge 32–35 kya according to Mal'ta . The ground zero extinction event appears to be Toba during which haplogroup CDEF* appeared to diverge into C, DE and F. C and F have almost nothing in common while D and E have plenty in common. Extinction event #1 according to current estimates occurred after Toba, although older ancient DNA could push

1620-437: The cell cycle where the cell is not dividing), two types of chromatin can be distinguished: In the early stages of mitosis or meiosis (cell division), the chromatin double helix becomes more and more condensed. They cease to function as accessible genetic material ( transcription stops) and become a compact transportable form. The loops of thirty-nanometer chromatin fibers are thought to fold upon themselves further to form

1680-502: The cytoplasm that contain cellular DNA and play a role in horizontal gene transfer . In prokaryotes and viruses, the DNA is often densely packed and organized; in the case of archaea, by homology to eukaryotic histones, and in the case of bacteria, by histone-like proteins. 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

1740-451: The endosymbiotic bacteria Candidatus Hodgkinia cicadicola and Candidatus Tremblaya princeps , to more than 14,000,000 base pairs in the soil-dwelling bacterium Sorangium cellulosum . Some bacteria have more than one chromosome. For instance, Spirochaetes such as Borrelia burgdorferi (causing Lyme disease ), contain a single linear chromosome. Vibrios typically carry two chromosomes of very different size. Genomes of

1800-563: The 16 chromosomes of yeast were fused into one giant chromosome, it was found that the cells were still viable with only somewhat reduced growth rates. The tables below give the total number of chromosomes (including sex chromosomes) in a cell nucleus for various eukaryotes. Most are diploid , such as humans who have 22 different types of autosomes —each present as two homologous pairs—and two sex chromosomes , giving 46 chromosomes in total. Some other organisms have more than two copies of their chromosome types, for example bread wheat which

1860-612: The Americas, and Melanesia, as well as in parts of the Horn of Africa and North Africa; almost none have been found in Europe. The N haplogroup may represent another macrolineage that evolved outside of Africa, heading northward instead of eastward. Shortly after the migration, the large R group split off from the N. Haplogroup R consists of two subgroups defined on the basis of their geographical distributions, one found in southeastern Asia and Oceania and

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1920-1351: The Horn of Africa and the Arabian Peninsula (Saudi Arabia, Yemen, Oman), separated only by a narrow strait between the Red Sea and the Gulf of Aden. CZ – Many Siberians; branch C – Some Amerindian; branch Z – Many Saami, some Korean, some North Chinese, some Central Asian populations. D – Some Amerindians, many Siberians and northern East Asians E – Malay, Borneo, Philippines, Taiwanese aborigines , Papua New Guinea G – Many Northeast Siberians, northern East Asians, and Central Asians Q – Melanesian, Polynesian, New Guinean populations The N type consists of: A – Found in many Amerindians and some East Asians and Siberians I – 10% frequency in Northern, Eastern Europe S – Some Indigenous Australian (First Nations People of Australia) W – Some Eastern Europeans, South Asians, and southern East Asians X – Some Amerindians, Southern Siberians, Southwest Asians, and Southern Europeans Y – Most Nivkhs and people of Nias ; many Ainus, Tungusic people , and Austronesians ; also found with low frequency in some other populations of Siberia, East Asia, and Central Asia R – Large group found within

1980-663: The Levant (modern Lebanon area), found in 25% frequency in Bedouin populations; branch JT (branch J; branch T) – North, Eastern Europe, Indus, Mediterranean U – High frequency in West Eurasia, Indian sub-continent, and Algeria, found from India to the Mediterranean and to the rest of Europe; U5 in particular shows high frequency in Scandinavia and Baltic countries with the highest frequency in

2040-841: The N type. Populations contained therein can be divided geographically into West Eurasia and East Eurasia. Almost all European populations and a large number of Middle-Eastern population today are contained within this branch. A smaller percentage is contained in other N type groups (See above). Below are subclades of R : B – Some Chinese, Tibetans, Mongolians, Central Asians, Koreans, Amerindians, South Siberians, Japanese, Austronesians F – Mainly found in southeastern Asia, especially Vietnam ; 8.3% in Hvar Island in Croatia. R0 – Found in Arabia and among Ethiopians and Somalis; branch HV (branch H; branch V) – Europe, Western Asia, North Africa; Pre-JT – Arose in

2100-467: The X chromosome at the ends of the Y chromosome ; the remaining 95% of the Y chromosome does not recombine. Therefore, the Y chromosome and any mutations that arise in it are passed down in a direct male line of descent. Other chromosomes, autosomes and X chromosomes (when another X chromosome is available to pair with it), share their genetic material during meiosis , the process of cell division which produces gametes . Effectively this means that

2160-715: The Y Chromosome Consortium. Y-chromosomal Adam is the name given by researchers to the male who is the most recent common patrilineal (male-lineage) ancestor of all living humans. Major Y-chromosome haplogroups, and their geographical regions of occurrence (prior to the recent European colonization), include: (mutation M168 occurred ~50,000 bp) (mutation M89 occurred ~45,000 bp) (mutation M9 occurred ~40,000 bp ) Human mtDNA haplogroups are lettered: A , B , C , CZ , D , E , F , G , H , HV , I , J , pre- JT , JT , K , L0 , L1 , L2 , L3 , L4 , L5 , L6 , M , N , O , P , Q , R , R0 , S , T , U , V , W , X , Y , and Z . The most up-to-date version of

2220-418: The alphabet, and refinements consist of additional number and letter combinations, such as (for example) A → A1 → A1a . The alphabetical nomenclature was published in 2002 by the Y Chromosome Consortium . In human genetics , the haplogroups most commonly studied are Y-chromosome (Y-DNA) haplogroups and mitochondrial DNA (mtDNA) haplogroups , each of which can be used to define genetic populations . Y-DNA

2280-423: 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. In the nuclear chromosomes of eukaryotes, the uncondensed DNA exists in

2340-507: The closest living relatives to modern humans, have 48 chromosomes as do the other great apes : in humans two chromosomes fused to form chromosome 2 . Chromosomal aberrations are disruptions in the normal chromosomal content of a cell. They can cause genetic conditions in humans, such as Down syndrome , although most aberrations have little to no effect. Some chromosome abnormalities do not cause disease in carriers, such as translocations , or chromosomal inversions , although they may lead to

2400-406: The compact metaphase chromosomes of mitotic cells. The DNA is thus condensed about ten-thousand-fold. The chromosome scaffold , which is made of proteins such as condensin , TOP2A and KIF4 , plays an important role in holding the chromatin into compact chromosomes. Loops of thirty-nanometer structure further condense with scaffold into higher order structures. This highly compact form makes

2460-559: The following are common divisions for mtDNA haplogroups: The mitochondrial haplogroups are divided into three main groups, which are designated by the sequential letters L, M, N. Humanity first split within the L group between L0 and L1-6. L1-6 gave rise to other L groups, one of which, L3, split into the M and N group. The M group comprises the first wave of human migration which is thought to have evolved outside of Africa, following an eastward route along southern coastal areas. Descendant lineages of haplogroup M are now found throughout Asia,

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2520-438: The genetic material from these chromosomes gets mixed up in every generation, and so any new mutations are passed down randomly from parents to offspring. The special feature that both Y chromosomes and mtDNA display is that mutations can accrue along a certain segment of both molecules and these mutations remain fixed in place on the DNA. Furthermore, the historical sequence of these mutations can also be inferred. For example, if

2580-473: The genus Burkholderia carry one, two, or three chromosomes. Prokaryotic chromosomes have less sequence-based structure than eukaryotes. Bacteria typically have a one-point (the origin of replication ) from which replication starts, whereas some archaea contain multiple replication origins. The genes in prokaryotes are often organized in operons and do not usually contain introns , unlike eukaryotes. Prokaryotes do not possess nuclei. Instead, their DNA

2640-460: The ground zero extinction event to long before Toba, and push the first extinction event here back to Toba. Haplogroups with extinction event notes by them have a dubious origin and this is because extinction events lead to severe bottlenecks, so all notes by these groups are just guesses. Note that the SNP counting of ancient DNA can be highly variable meaning that even though all these groups diverged around

2700-459: The histones bind to and condense the DNA molecule to maintain its integrity. These eukaryotic chromosomes display a complex three-dimensional structure that has a significant role in transcriptional regulation . Normally, chromosomes are visible under a light microscope only during the metaphase of cell division , where all chromosomes are aligned in the center of the cell in their condensed form. Before this stage occurs, each chromosome

2760-583: The independent work of Boveri and Sutton (both around 1902) by naming the chromosome theory of inheritance the ' Boveri–Sutton chromosome theory ' (sometimes known as the 'Sutton–Boveri chromosome theory'). Ernst Mayr remarks that the theory was hotly contested by some famous geneticists, including William Bateson , Wilhelm Johannsen , Richard Goldschmidt and T.H. Morgan , all of a rather dogmatic mindset. Eventually, absolute proof came from chromosome maps in Morgan's own laboratory. The number of human chromosomes

2820-509: 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; q-g "grande"; alternatively it is sometimes said q is short for queue meaning tail in French ). This

2880-494: 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 during fertilization , a new diploid organism is formed. Some animal and plant species are polyploid [Xn], having more than two sets of homologous chromosomes . Important crops such as tobacco or wheat are often polyploid, compared to their ancestral species. Wheat has

2940-429: The membranes (and the attached DNA). 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 . Each eukaryotic chromosome consists of a long linear DNA molecule associated with proteins , forming a compact complex of proteins and DNA called chromatin . Chromatin contains

3000-468: The mtDNA tree is maintained by Mannis van Oven on the PhyloTree website. Phylogenetic tree of human mitochondrial DNA (mtDNA) haplogroups Mitochondrial Eve is the name given by researchers to the woman who is the most recent common matrilineal (female-lineage) ancestor of all living humans. Haplogroups can be used to define genetic populations and are often geographically oriented. For example,

3060-458: The other containing almost all of the modern European populations. Haplogroup N(xR), i.e. mtDNA that belongs to the N group but not to its R subgroup, is typical of Australian aboriginal populations, while also being present at low frequencies among many populations of Eurasia and the Americas. The L type consists of nearly all Africans. The M type consists of: M1 – Ethiopian, Somali and Indian populations. Likely due to much gene flow between

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3120-486: The risk of aneuploid spermatozoa. In particular, risk of aneuploidy is increased by tobacco smoking, and occupational exposure to benzene, insecticides, and perfluorinated compounds. Increased aneuploidy is often associated with increased DNA damage in spermatozoa. The number of chromosomes in eukaryotes is highly variable. It is possible for chromosomes to fuse or break and thus evolve into novel karyotypes. Chromosomes can also be fused artificially. For example, when

3180-438: The same in all body cells. However, asexual species can be either haploid or diploid. Sexually reproducing species have somatic cells (body cells) that are diploid [2n], having two sets of chromosomes (23 pairs in humans), one set from the mother and one from the father. Gametes (reproductive cells) are haploid [n], having one set of chromosomes. Gametes are produced by meiosis of a diploid germline cell, during which

3240-445: The same time no one knows when. Y-Chromosome Chromosome This is an accepted version of this page A chromosome is a package of DNA containing part or all of the genetic material of an organism . In most chromosomes, the very long thin DNA fibers are coated with nucleosome -forming packaging proteins ; in eukaryotic cells, the most important of these proteins are the histones . Aided by chaperone proteins ,

3300-594: The set of chromosomes arranged, autosomes in order of length, and sex chromosomes (here X/Y) at the end. Like many sexually reproducing species, humans have special gonosomes (sex chromosomes, in contrast to autosomes ). These are XX in females and XY in males. 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 . In 1922, Painter

3360-537: The title Haplo . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Haplo&oldid=897749179 " Categories : Disambiguation pages Fish common name disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Haplogroup Each haplogroup originates from, and remains part of,

3420-459: The vast majority of the DNA in an organism, but a small amount inherited maternally can be found in the mitochondria . It is present in most cells , with a few exceptions, for example, red blood cells . Histones are responsible for the first and most basic unit of chromosome organization, the nucleosome . Eukaryotes ( cells with nuclei such as those found in plants, fungi, and animals) possess multiple large linear chromosomes contained in

3480-422: Was also a direct male line descendant of this man, but is also the direct male line ancestor of all men carrying mutation B. Series of mutations such as this form molecular lineages. Furthermore, each mutation defines a set of specific Y chromosomes called a haplogroup. All humans carrying mutation A form a single haplogroup, and all humans carrying mutation B are part of this haplogroup, but mutation B also defines

3540-440: Was not certain whether the diploid number of man is 46 or 48, at first favouring 46. He revised his opinion later from 46 to 48, and he correctly insisted on humans having an XX/XY system. New techniques were needed to definitively solve the problem: It took until 1954 before the human diploid number was confirmed as 46. Considering the techniques of Winiwarter and Painter, their results were quite remarkable. Chimpanzees ,

3600-544: Was published by Painter in 1923. By inspection through a microscope, he counted 24 pairs of chromosomes, giving 48 in total. His error was copied by others, and it was not until 1956 that the true number (46) was determined by Indonesian-born cytogeneticist Joe Hin Tjio . The prokaryotes  – bacteria and archaea  – typically have a single circular chromosome . The chromosomes of most bacteria (also called genophores ), can range in size from only 130,000 base pairs in

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