Instruct: Given a question, retrieve passages that can help answer the question.
Query: How large is chromosome 6?
Chromosome 6 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 6 spans more than 170 million base pairs (the building material of DNA) and represents between 5.5 and 6% of the total DNA in cells. It contains the Major Histocompatibility Complex, which contains over 100 genes related to the immune response, and plays a vital role in organ transplantation.
Lepidoptera also do not show the classical breakage-fusion-bridge cycle that is a characteristic of dominant lethals induced in Diptera. It appears that lepidopteran chromosomes can tolerate telomere loss without the drastic effects that this has on chromosomes in other orders. Lepidopteran chromosomes possess a localized kinetochore plate to which the spindle microtubules attach during cell division. The kinetochore plates are large and cover a significant portion of the chromosome length, ensuring that more radiation-induced breaks will not lead to the loss of chromosome fragments as is typical in species with monocentric chromosomes. In species with large kinetochore plates, the fragments may persist for a number of mitotic cell divisions, and can even be transmitted through germ cells to the next generation. The plates also reduce the risk of lethality caused by the formation of dicentric chromosomes, acentric fragments, and other unstable aberrations.
A linear chromosome is a type of chromosome, found in most eukaryotic cells, in which the DNA is arranged in multiple linear molecules of DNA. In contrast, most prokaryotic cells contain circular chromosomes, where the DNA is arranged in one large circular molecule. However, linear chromosomes are not limited to eukaryotic organisms; some prokaryotic organisms do have linear chromosomes as well, such as "Borrelia burgdorferi". It is possible to take a prokaryotic cell with a circular chromosome, linearize the chromosome, and still have a viable organism.
The diploid chromosome number of "M. umbrosus" is 56 and the fundamental number is 60. Along with the species "M. quasiater", they present the highest diploid chromosomal complement of the Mexican vole species. The karotype consists of three pairs of small to medium-sized metacentric chromosomes and 24 pairs of telocentric chromosomes. The X chromosome is a large metacentric chromosome and the Y a small telocentric. The Y chromosome of "M. umbrosus", "M. quasiater", "M. mexicanus", and "M. oaxacensis" all display the same centrometric positioning.
The following diseases are some of those related to genes on chromosome 6:
In 2005 Vezzi et al. published the genome sequence for "P. profundum" strain SS9. The genome of "P. profundum" consists of a 4.1-Mbp circular chromosome, a 2.2-Mbp minor circular chromosome, as well as an 80-kbp circular plasmid. Strain SS9 has 14 ribosomal RNA (rRNA) genes on chromosome 1, and 1 on chromosome 2; this is the largest number of rRNA genes found in any bacterium. Chromosome 1 consists largely of genes which are essential for growth whereas chromosome 2 appears to be a large plasmid, which, on an evolutionary time scale, has gained several transposable elements. Within the genome of "P. profundum" there is a large number of open reading frames (ORF) which are unique to SS9 and not found in other members of the "Vibrionaceae" family.
Genetic analysis techniques have led to the identification of chromosomal abnormalities associated with metastatic tumor progression in uveal melanoma. Loss of heterozygosity, loss of entire alleles from chromosomes, partial chromosomal addition and deletion and single nucleotide polymorphisms (SNP) have been associated with uveal melanoma metastatic lesions. In particular, chromosomes 1, 3, 6 and 8 have been extensively studied for their association with shorter survival time and development of metastatic disease. While genetic aberrations in chromosomes 1, 6 and 8 have not independently been able to predict disease progression, cytogenetic profiling of chromosome 3 has uncovered an important genetic region highly associated with metastatic onset in uveal melanoma patients. Chromosome 3 abnormalities have been analyzed using multiple techniques, including fluorescence in situ hybridization (FISH), chromosomal in situ hybridization (CISH), array comparative genomic hybridization (aCGH), SNP, multiplex ligation-dependent probe amplification (MLPA), and microsatellite analysis. Despite a wealth of data that has identified the association of chromosome 3 mutation with UM metastasis, the clinical application of this data has yet to be realized. Reasons for the uncertainty of chromosome 3 clinical use include 1) high false-positive rates (ranging from 5-22%), 2) high false-negative rates (ranging from 4-50%), 3) high technical failure rates (up to 50%) due to the large tissue requirement for current analysis techniques, and 4) the adverse effects of cellular heterogeneity on chromosome 3 cytogenetic analysis. Furthermore, unlike the DecisionDx-UM test, there are no published, peer-reviewed studies that demonstrate clinical validation in an independent set of patients.
The human leukocyte antigen lies on chromosome 6, with the exception of the gene for β2-microglobulin (which is located on chromosome 15), and encodes cell-surface antigen-presenting proteins among other functions.
Thus, dosage compensation in mammals is largely achieved through the silencing of one of two female X chromosomes via X-inactivation. This process involves histone tail modifications, DNA methylation patterns, and reorganization of large-scale chromatin structure encoded by the X-ist gene. In spite of these extensive modifications, not all genes along the X chromosome are subject to X-inactivation; active expression at some loci is required for homologous recombination with the pseudo-autosomal region (PAR) of the Y chromosome during meiosis. Additionally, 10-25% of human X chromosome genes, and 3-7% of mouse X chromosome genes outside of the PARs show weak expression from the inactive X chromosome.
To focus more on the offspring and how it results in the formation of the f1 generation, is an inheritance called sex-linkage, which is a gene which is located on the sex chromosome and patterns of these inheritance differ in both male and female. The explanation that proves the theory of the offspring having genes from both parent generations, is proven through a process called crossing-over, which consists of taking genes from the male chromosomes and genes from the female chromosome, resulting in a process of meiosis occurring, and leading to the splitting of the chromosomes evenly. Depending on which genes are dominantly expressed in the gene will result in the sex of the offspring. The female will always give an X chromosome, whereas the male, depending on the situation, will either give an X chromosome or a Y chromosome. If a male offspring is produced, the gene will consist of an X and a Y chromosome. If two X chromosomes are expressed and produced, it produces a female offspring.
Chromatin diminution is a process of partial elimination of chromatin genetic material from genome of prospective somatic cells. This process was found to occur during the early developmental stage in three groups: nematodes, copepods, and hagfish One of the first studies regarding somatic genome processing was observed by Boveri large-scale chromatin elimination in parasitic nematode "Parascaris univalens". During chromatin diminution, somatic chromosomes becomes fragmented with new telomeres added in many different places and devoid of heterochromatin so it differs from germline cell in respect of structure and genetic content. Germline cells of "P. univalens" contain only two chromosomes, but in early embryogenesis central euchromatic regions of the chromosomes fragment into diploid somatic set of 2×29 autosomes and 2×6 X chromosomes in females or 2×29 autosomes and 6 X chromosomes in males, which segregate to the two daughter nuclei. After all heterochromatin becomes degraded in cytoplasm. As a result of chromatin diminution "P. univalens loses about" 80–90% of the total nuclear germ line DNA.
Nettie Maria Stevens (July 7, 1861 – May 4, 1912) was an early American geneticist. She discovered sex chromosomes in the same year but slightly earlier than Edmund Beecher Wilson. In 1905, soon after the rediscovery of Mendel's paper on genetics in 1900, she discovered that male mealworms produced two kinds of sperm, one with a large chromosome and one with a small chromosome. When the sperm with the large chromosome fertilized eggs, they produced female offspring, and when the sperm with the small chromosome fertilized eggs, they produced male offspring. She and Wilson both credited her with the discovery of sex chromosomes, but later scientists disagreed about who made the discovery. The pair of sex chromosomes that she studied later became known as the X and Y chromosomes.
The ZW sex-determination system is found in birds, some reptiles, and some insects and other organisms. The ZW sex-determination system is reversed compared to the XY system: females have two different kinds of chromosomes (ZW), and males have two of the same kind of chromosomes (ZZ). In the chicken, this was found to be dependent on the expression of DMRT1. In birds, the genes FET1 and ASW are found on the W chromosome for females, similar to how the Y chromosome contains SRY. However, not all species depend upon the W for their sex. For example, there are moths and butterflies that are ZW, but some have been found female with ZO, as well as female with ZZW. Also, while mammals deactivate one of their extra X chromosomes when female, it appears that in the case of Lepidoptera, the males produce double the normal amount of enzymes, due to having two Z's. Because the use of ZW sex determination is varied, it is still unknown how exactly most species determine their sex. However, reportedly, the silkworm "Bombyx mori" uses a single female-specific piRNA as the primary determiner of sex. Despite the similarities between the ZW and XY systems, these sex chromosomes evolved separately. In the case of the chicken, their Z chromosome is more similar to humans' autosome 9. The chicken's Z chromosome also seems to be related to the X chromosome of the platypus. When a ZW species, such as the Komodo dragon, reproduces parthenogenetically, usually only males are produced. This is due to the fact that the haploid eggs double their chromosomes, resulting in ZZ or WW. The ZZ become males, but the WW are not viable and are not brought to term.
"Aprasia parapulchella" cells have 42 chromosomes in the diploid state. Males of the species have a heteromorphic pair of chromosomes (a pair of two different ones), termed XY, and the females have a pair of same XX chromosomes. The microsatellite (AGAT) is strongly repeated near the Y chromosome centromere. The Y chromosome also contains the (AC) motif, whereas the X chromosome does not. (AC) also shows up on another two pairs of small and large chromosomes.
In 2000, Dernburg started up her laboratory at Lawrence Berkeley National Laboratory and the University of California, Berkeley to continue investigating chromosome organization and dynamics, focusing on meiosis using the nematode worm "Caenorhabditis elegans" as a model organism. Her laboratory has contributed to the community's understanding of how chromosomes find and pair with the appropriate homolog during meiosis, which is essential for proper chromosome segregation and ensuring the appropriate chromosome copy number in daughter cells. Her group has worked to understand how special regions of chromosomes, known as pairing centers, promote homologous chromosome pairing, synapsis, and segregation in the worm. In 2005, they published a study demonstrating how pairing centers perform two separable functions during meiosis. First, they facilitate pairing through stabilizing an intermediate complex involved in the pairing process. Second, pairing centers promote the formation of a synaptonemal complex, in which a protein polymer acts as a scaffold to hold homologous chromosomes together during recombination. In a related study, her group also uncovered a conserved meiotic checkpoint that acts during meiosis to recognize unpaired/unsynapsed chromosomes. Cells identified as having unsynapsed chromosomes undergo apoptosis, or programmed cell death, to guard against the formation of sex cells with the wrong number of chromosomes.
Linear chromosomes have a few advantages and disadvantages to circular chromosomes. One reason that many organisms have evolved to having linear chromosomes is the size of their genome. Linear chromosomes make it easier for transcription and replication of large genomes. If an organism had a very large genome arranged in a circular chromosome, it would have the potential problems when unwinding due to torsional strain. As mentioned before, linear chromosomes are not perfect and have their disadvantages; the biggest being the terminal ends of the chromosomes, or telomeres. Generally, telomeres tend to be unstable and lead to mutations or tumors. Additionally, due to the methods of DNA replication the ends of the telomeres will not completely be replicated and will be lost, which is known as the "end replication problem". Most eukaryotic cells are able to prevent crucial DNA from being lost by the use of telomerase, an enzyme that synthesizes telomeric DNA, which allows the telomeric DNA to be cut short instead of cutting crucial DNA. Lastly, even though an organism may have evolved to having linear chromosomes, it is still possible for said organism to revert to having a circular chromosome. When this happens, the organism will essentially delete part of or all of its telomere ends of their linear chromosomes and recombine the strands into the circular shape.
The diploid number of chromosomes in the wildebeest is 58.[20] Chromosomes were studied in a male and a female wildebeest. In the female, all except a pair of very large submetacentric chromosomes were found to be acrocentric. Metaphases were studied in the male's chromosomes, and very large submetacentric chromosomes were found there, as well, similar to those in the female both in size and morphology. Other chromosomes were acrocentric. The X chromosome is a large acrocentric and the Y chromosome a minute one.[11][21]
Chromosome 5 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 5 spans about 181 million base pairs (the building blocks of DNA) and represents almost 6% of the total DNA in cells. Chromosome 5 is the 5th largest human chromosome, yet has one of the lowest gene densities. This is partially explained by numerous gene-poor regions that display a remarkable degree of non-coding and syntenic conservation with non-mammalian vertebrates, suggesting they are functionally constrained.
Chromosome 4 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 4 spans more than 186 million base pairs (the building material of DNA) and represents between 6 and 6.5 percent of the total DNA in cells.
Chromom–Chromop
Chromos
Chromosoma
Chromosome
Chromosome 1
Chromosome 10 – Chromosome 12
Chromosome 13 – Chromosome 15
Chromosome 16 – Chromosome 1q
Chromosome 2
Chromosome 20 – Chromosome 22
Chromosome 3
Chromosome 4 – Chromosome 5
Chromosome 6 – Chromosome 7
Chromosome 8 – Chromosome 9
Chromosomes
Congenital a – Congenital b
Congenital c – Congenital g
Congenital h – Congenital l
Congenital m – Congenital s
Congenital t – Congenital vCranioa–Craniom
Cranios–Craniot
The blackbuck shows variation in its diploid chromosome number. Males have 31-33 while females have 30-32. Males have a XY1Y2 sex chromosome. Unusually large sex chromosomes had earlier been described only in a few species, all of which belonged to Rodentia. However, in 1968, a study found that two artiodactyls, the blackbuck and the sitatunga, too showed this abnormality. Generally the X chromosome constitutes 5 percent of the haploid chromosomal complement; but the X chromosome of the blackbuck this percentage is 14.96. Portions of both peculiarly large chromosomes show delayed replication.
Unlike other chromosomes, Y chromosomes generally do not come in pairs. Every human male (excepting those with XYY syndrome) has only one copy of that chromosome. This means that there is not any chance variation of which copy is inherited, and also (for most of the chromosome) not any shuffling between copies by recombination; so, unlike autosomal haplotypes, there is effectively not any randomisation of the Y-chromosome haplotype between generations. A human male should largely share the same Y chromosome as his father, give or take a few mutations; thus Y chromosomes tend to pass largely intact from father to son,
with a small but accumulating number of mutations that can serve to differentiate male lineages.
In particular, the Y-DNA represented as the numbered results of a Y-DNA genealogical DNA test should match, except for mutations.
The Micronuclei model is the most accepted model as to how and when the breakage and repair in chromothripsis occurs. 
In cancer cells, fragmentation of chromosomes has been correlated with the presence of micronuclei. Micronuclei are structures formed by mitotic errors in the transition from metaphase to anaphase. Cells with defective chromosome segregation will form micronuclei which contain whole chromosomes or fragments of chromosomes. The segregation of single chromosomes into individual micronuclei explains why DNA fragmentation is isolated to single chromosomes in chromothripsis.
The diploid number of chromosomes in the blue wildebeest is 58. Chromosomes were studied in a male and a female wildebeest. In the female, all except a pair of very large submetacentric chromosomes were found to be acrocentric. Metaphases were studied in the male's chromosomes, and very large submetacentric chromosomes were found there, as well, similar to those in the female both in size and morphology. the rest were acrocentric. The X chromosome is a large acrocentric, while the Y chromosome is a minute one.
The animal has a karyotype of 2n=44 and FN=54, which consists of five pairs of four-armed chromosomes and sixteen pairs of two-armed (telocentric) chromosomes. The X-chromosome is a large, and the Y-chromosome a small telocentric chromosome. This karyotype has much in common with that of the least forest mouse ("Apomys musculus"), while at the same time being very different from the karyotypes of species form other parts of the Philippines (the karyotype of the large Mindoro forest mouse, on a side note, is unknown).