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Index X-inactivation

X-inactivation (also called lyonization) is a process by which one of the copies of the X chromosome present in female mammals is inactivated. [1]

84 relations: Adrenoleukodystrophy, Allele, Aneuploidy, Autosome, Barr body, Blastocyst, Calico cat, Cell cycle, Cell nucleus, Chromosomal translocation, DAPI, DNA, DNA methylation, DNA replication, Dosage compensation, Down syndrome, Duchenne muscular dystrophy, Embryo, Epiblast, Epigenetics, Epilepsy-intellectual disability in females, Ernest Beutler, Euchromatin, Eutheria, Female, Fluorescence in situ hybridization, Frontonasal dysplasia, Ftx (gene), Gastrulation, Gene, Gene product, Gene silencing, Genomic imprinting, Genotype, Germ cell, Germline, Glucose-6-phosphate dehydrogenase, H2AFY, Heterochromatin, Histone, Histone acetyltransferase, Histone H3, Histone methylation, Human, Induced pluripotent stem cell, Inner cell mass, Jpx (gene), Klinefelter syndrome, Long non-coding RNA, Male, ..., Mammal, Mammalian embryogenesis, Marsupial, Mary F. Lyon, Maternal to zygotic transition, Meiosis, Mosaic (genetics), Necessity and sufficiency, Neil Brockdorff, Non-coding RNA, Nucleosome, Oocyte, Ovulation, Phenotypic trait, Placenta, Polycomb recruitment in X chromosome inactivation, Pseudoautosomal region, Regulation of gene expression, RNA, Sense (molecular biology), Sex linkage, Sex-determination system, Skewed X-inactivation, Stanley Michael Gartler, Susumu Ohno, Tortoiseshell cat, Transcription (biology), Translation (biology), Tsix, Turner syndrome, X chromosome, XIST, Y chromosome, Zygosity. Expand index (34 more) »


Adrenoleukodystrophy is a disease linked to the X chromosome.

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An allele is a variant form of a given gene.

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Aneuploidy is the presence of an abnormal number of chromosomes in a cell, for example a human cell having 45 or 47 chromosomes instead of the usual 46.

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An autosome is a chromosome that is not an allosome (a sex chromosome).

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Barr body

A Barr body (named after discoverer Murray Barr) is the inactive X chromosome in a female somatic cell, rendered inactive in a process called lyonization, in those species in which sex is determined by the presence of the Y (including humans) or W chromosome rather than the diploidy of the X. The Lyon hypothesis states that in cells with multiple X chromosomes, all but one are inactivated during mammalian embryogenesis.

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The blastocyst is a structure formed in the early development of mammals.

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Calico cat

Calico cats are domestic cats with a spotted or particolored coat that is predominantly white, with patches of two other colors (often orange and black).

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Cell cycle

The cell cycle or cell-division cycle is the series of events that take place in a cell leading to its division and duplication of its DNA (DNA replication) to produce two daughter cells.

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Cell nucleus

In cell biology, the nucleus (pl. nuclei; from Latin nucleus or nuculeus, meaning kernel or seed) is a membrane-enclosed organelle found in eukaryotic cells.

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Chromosomal translocation

In genetics, a chromosome translocation is a chromosome abnormality caused by rearrangement of parts between nonhomologous chromosomes.

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DAPI, or 4′,6-diamidino-2-phenylindole, is a fluorescent stain that binds strongly to adenine–thymine rich regions in DNA.

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Deoxyribonucleic acid (DNA) is a thread-like chain of nucleotides carrying the genetic instructions used in the growth, development, functioning and reproduction of all known living organisms and many viruses.

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DNA methylation

DNA methylation is a process by which methyl groups are added to the DNA molecule.

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DNA replication

In molecular biology, DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule.

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Dosage compensation

Dosage compensation is the process by which organisms equalize the expression of genes between members of different biological sexes.

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Down syndrome

Down syndrome (DS or DNS), also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21.

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Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a severe type of muscular dystrophy.

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An embryo is an early stage of development of a multicellular diploid eukaryotic organism.

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In amniote animal embryology, the epiblast (also known as the primitive ectoderm) is one of two distinct layers arising from the inner cell mass in the mammalian blastocyst or from the blastodisc in reptiles and birds.

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Epigenetics is the study of heritable changes in gene function that do not involve changes in the DNA sequence.

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Epilepsy-intellectual disability in females

Epilepsy-intellectual disability in females also known as PCDH19 gene-related epilepsy or epileptic encephalopathy, early infantile, 9 (EIEE9), is a rare type of epilepsy that affects predominately females and is characterized by clusters of brief seizures, which start in infancy or early childhood, and is occasionally accompanied by varying degrees of cognitive impairment.

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Ernest Beutler

Ernest Beutler (September 30, 1928 – October 5, 2008) was a German-born American hematologist and biomedical scientist.

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Euchromatin is a lightly packed form of chromatin (DNA, RNA, and protein) that is enriched in genes, and is often (but not always) under active transcription.

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Eutheria (from Greek εὐ-, eu- "good" or "right" and θηρίον, thēríon "beast" hence "true beasts") is one of two mammalian clades with extant members that diverged in the Early Cretaceous or perhaps the Late Jurassic.

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Female (♀) is the sex of an organism, or a part of an organism, that produces non-mobile ova (egg cells).

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Fluorescence in situ hybridization

Fluorescent in situ hybridization (FISH) is a molecular cytogenetic technique that uses fluorescent probes that bind to only those parts of the chromosome with a high degree of sequence complementarity.

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Frontonasal dysplasia

Frontonasal dysplasia (FND) is a congenital malformation of the midface.

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Ftx (gene)

In molecular biology, FTX transcript, XIST regulator (non-protein coding), also known as FTX (Five prime to Xist), is a long non-coding RNA.

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Gastrulation is a phase early in the embryonic development of most animals, during which the single-layered blastula is reorganized into a multilayered structure known as the gastrula.

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In biology, a gene is a sequence of DNA or RNA that codes for a molecule that has a function.

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Gene product

A gene product is the biochemical material, either RNA or protein, resulting from expression of a gene.

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Gene silencing

Gene silencing is the regulation of gene expression in a cell to prevent the expression of a certain gene.

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Genomic imprinting

Genomic imprinting is an epigenetic phenomenon that causes genes to be expressed in a parent-of-origin-specific manner.

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The genotype is the part of the genetic makeup of a cell, and therefore of an organism or individual, which determines one of its characteristics (phenotype).

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Germ cell

A germ cell is any biological cell that gives rise to the gametes of an organism that reproduces sexually.

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In biology and genetics, the germline in a multicellular organism is the population of its bodily cells that are so differentiated or segregated that in the usual processes of reproduction they may pass on their genetic material to the progeny.

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Glucose-6-phosphate dehydrogenase

Glucose-6-phosphate dehydrogenase (G6PD or G6PDH) is a cytosolic enzyme that catalyzes the chemical reaction This enzyme participates in the pentose phosphate pathway (see image), a metabolic pathway that supplies reducing energy to cells (such as erythrocytes) by maintaining the level of the co-enzyme nicotinamide adenine dinucleotide phosphate (NADPH).

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Core histone macro-H2A.1 is a protein that in humans is encoded by the H2AFY gene.

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Heterochromatin is a tightly packed form of DNA or condensed DNA, which comes in multiple varieties.

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In biology, histones are highly alkaline proteins found in eukaryotic cell nuclei that package and order the DNA into structural units called nucleosomes.

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Histone acetyltransferase

Histone acetyltransferases (HATs) are enzymes that acetylate conserved lysine amino acids on histone proteins by transferring an acetyl group from acetyl-CoA to form ε-N-acetyllysine.

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Histone H3

Histone H3 is one of the five main histone proteins involved in the structure of chromatin in eukaryotic cells.

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Histone methylation

Histone methylation is a process by which methyl groups are transferred to amino acids of histone proteins that make up nucleosomes, which the DNA double helix wraps around to form chromosomes.

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Humans (taxonomically Homo sapiens) are the only extant members of the subtribe Hominina.

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Induced pluripotent stem cell

Induced pluripotent stem cells (also known as iPS cells or iPSCs) are a type of pluripotent stem cell that can be generated directly from adult cells.

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Inner cell mass

In early embryogenesis of most eutherian mammals, the inner cell mass (abbreviated ICM and also known as the embryoblast in mammals or pluriblast) is the mass of cells inside the primordial embryo that will eventually give rise to the definitive structures of the fetus.

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Jpx (gene)

In molecular biology, JPX transcript, XIST activator (non-protein coding), also known as Jpx, is a long non-coding RNA.

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Klinefelter syndrome

Klinefelter syndrome (KS) also known as 47,XXY or XXY, is the set of symptoms that result from two or more X chromosomes in males.

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Long non-coding RNA

Long non-coding RNAs (long ncRNAs, lncRNA) are defined as transcripts longer than 200 nucleotides that are not translated into protein.

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A male (♂) organism is the physiological sex that produces sperm.

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Mammals are the vertebrates within the class Mammalia (from Latin mamma "breast"), a clade of endothermic amniotes distinguished from reptiles (including birds) by the possession of a neocortex (a region of the brain), hair, three middle ear bones, and mammary glands.

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Mammalian embryogenesis

Mammalian embryogenesis is the process of cell division and cellular differentiation during early prenatal development which leads to the development of a mammalian embryo.

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Marsupials are any members of the mammalian infraclass Marsupialia.

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Mary F. Lyon

Mary Frances Lyon (15 May 1925 – 25 December 2014) was an English geneticist, best known for her discovery of X-chromosome inactivation, an important biological phenomenon.

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Maternal to zygotic transition

Maternal to zygotic transition (MZT) is the stage in embryonic development during which development comes under the exclusive control of the zygotic genome.

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Meiosis (from Greek μείωσις, meiosis, which means lessening) is a specialized type of cell division that reduces the chromosome number by half, creating four haploid cells, each genetically distinct from the parent cell that gave rise to them.

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Mosaic (genetics)

In genetics, a mosaic, or mosaicism, involves the presence of two or more populations of cells with different genotypes in one individual, who has developed from a single fertilized egg.

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Necessity and sufficiency

In logic, necessity and sufficiency are terms used to describe an implicational relationship between statements.

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Neil Brockdorff

Neil Brockdorff is a Wellcome Trust Principal Research Fellow and professor in the department of biochemistry at the University of Oxford.

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Non-coding RNA

A non-coding RNA (ncRNA) is an RNA molecule that is not translated into a protein.

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A nucleosome is a basic unit of DNA packaging in eukaryotes, consisting of a segment of DNA wound in sequence around eight histone protein cores.

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An oocyte, oöcyte, ovocyte, or rarely ocyte, is a female gametocyte or germ cell involved in reproduction.

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Ovulation is the release of eggs from the ovaries.

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Phenotypic trait

A phenotypic trait, or simply trait, is a distinct variant of a phenotypic characteristic of an organism; it may be either inherited or determined environmentally, but typically occurs as a combination of the two.

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The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, thermo-regulation, waste elimination, and gas exchange via the mother's blood supply; to fight against internal infection; and to produce hormones which support pregnancy.

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Polycomb recruitment in X chromosome inactivation

Recruitment of polycomb proteins in X chromosome inactivation X chromosome inactivation (XCI) is the phenomenon that has been selected during the evolution to balance X-linked gene dosage between XX females and XY males.

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Pseudoautosomal region

The pseudoautosomal regions, PAR1, PAR2, are homologous sequences of nucleotides on the X and Y chromosomes.

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Regulation of gene expression

Regulation of gene expression includes a wide range of mechanisms that are used by cells to increase or decrease the production of specific gene products (protein or RNA), and is informally termed gene regulation.

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Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation, and expression of genes.

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Sense (molecular biology)

In molecular biology and genetics, the sense of nucleic acid molecules (often DNA or RNA) is the nature of their roles and their complementary molecules' nucleic acid units' roles in specifying amino acids.

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Sex linkage

Sex linkage is the phenotypic expression of an allele related to the allosome (sex chromosome) of the individual.

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Sex-determination system

A sex-determination system is a biological system that determines the development of sexual characteristics in an organism.

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Skewed X-inactivation

Skewed X chromosome inactivation occurs when the inactivation of one X chromosome is favored over the other, leading to an uneven number of cells with each chromosome inactivated.

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Stanley Michael Gartler

Stanley Michael Gartler (born June 9, 1923) is a cell and molecular biologist and human geneticist.

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Susumu Ohno

was a Japanese-American geneticist and evolutionary biologist, and seminal researcher in the field of molecular evolution.

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Tortoiseshell cat

Tortoiseshell is a cat coat coloring named for its similarity to tortoiseshell material.

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Transcription (biology)

Transcription is the first step of gene expression, in which a particular segment of DNA is copied into RNA (especially mRNA) by the enzyme RNA polymerase.

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Translation (biology)

In molecular biology and genetics, translation is the process in which ribosomes in the cytoplasm or ER synthesize proteins after the process of transcription of DNA to RNA in the cell's nucleus.

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Tsix is a non-coding RNA gene that is antisense to the Xist RNA.

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Turner syndrome

Turner syndrome (TS), also known as 45,X or 45,X0, is a condition in which a female is partly or completely missing an X chromosome.

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X chromosome

The X chromosome is one of the two sex-determining chromosomes (allosomes) in many organisms, including mammals (the other is the Y chromosome), and is found in both males and females.

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Xist (X-inactive specific transcript) is an RNA gene on the X chromosome of the placental mammals that acts as a major effector of the X inactivation process.

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Y chromosome

The Y chromosome is one of two sex chromosomes (allosomes) in mammals, including humans, and many other animals.

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Zygosity is the degree of similarity of the alleles for a trait in an organism.

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Redirects here:

Lionisation, Lyon Hypothesis, Lyon effect, Lyon hypothesis, Lyonisation, Lyonization, Random X-inactivation, X chromosome inactivation, X inactivation, X-chromosome inactivation, X-inactivations, XCI.


[1] https://en.wikipedia.org/wiki/X-inactivation

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