Y chromosome

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Y chromosome

genetics

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July 23, 2026

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The Y chromosome is a sex chromosome characteristic of male cells in species where males have two unlike sex chromosomes. In humans, sex chromosomes are designated as X and Y. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). The Y chromosome directs the development of embryonic gonads into testes in XY fetuses.123

The Y chromosome is generally smaller than the X chromosome and carries fewer genes. Most genes on the Y chromosome are related to maleness. Traits controlled by genes on the X chromosome are called sex-linked and occur more frequently in males because they lack a corresponding gene on the Y chromosome to counteract its effects. For example, hemophilia and red-green color blindness are sex-linked traits.24

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Homo sapiens
Bodily structure
…mtDNA samples, as well as Y chromosome samples, derived from people all over the world point to the common descent of all modern humans from a small population that existed about 150 kya. In addition, the African samples show more variability in their mtDNA than do those of other continents,…
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…mtDNA samples, as well as Y chromosome samples, derived from people all over the world point to the common descent of all modern humans from a small population that existed about 150 kya. In addition, the African samples show more variability in their mtDNA than do those of other continents,…
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human disease
Diseases of genetic origin
…no complementary genes on the Y chromosome. Females have two copies of the X chromosome, but males have an X and a Y chromosome. Because males have only one copy of the X chromosome, any mutation occurring in a gene on this chromosome will be expressed in male offspring regardless…
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…no complementary genes on the Y chromosome. Females have two copies of the X chromosome, but males have an X and a Y chromosome. Because males have only one copy of the X chromosome, any mutation occurring in a gene on this chromosome will be expressed in male offspring regardless…
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Genographic Project
Exploring human migration
…researchers focused specifically on the Y chromosome of males and the mitochondrial DNA (mtDNA) of males and females. The Y chromosome allows the paternal lineage of males to be traced back many generations, in part because it contains regions of DNA that do not undergo recombination (the mixing of genetic…
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…researchers focused specifically on the Y chromosome of males and the mitochondrial DNA (mtDNA) of males and females. The Y chromosome allows the paternal lineage of males to be traced back many generations, in part because it contains regions of DNA that do not undergo recombination (the mixing of genetic…
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sex chromosome
…by scientists as X and Y. In humans the sex chromosomes consist of one pair of the total of 23 pairs of chromosomes. The other 22 pairs of chromosomes are called autosomes.
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…by scientists as X and Y. In humans the sex chromosomes consist of one pair of the total of 23 pairs of chromosomes. The other 22 pairs of chromosomes are called autosomes.
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metabolic disease
Inheritance
…have an X and a Y chromosome. If a mutant gene is part of the X chromosome, the resulting disease is called X-linked. All male offspring who inherit an X-linked mutation are affected, because the Y chromosome of the XY pair does not have a compensating normal gene. Because the…
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…have an X and a Y chromosome. If a mutant gene is part of the X chromosome, the resulting disease is called X-linked. All male offspring who inherit an X-linked mutation are affected, because the Y chromosome of the XY pair does not have a compensating normal gene. Because the…
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sex-linked character
…carries many genes, whereas the Y, or male-determining, chromosome is deficient in genes. A woman has two X chromosomes; a man has one X chromosome and one Y chromosome. Several traits, including red-green colour blindness, arise from the interaction of genes that are located on the X chromosome. A man…
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…carries many genes, whereas the Y, or male-determining, chromosome is deficient in genes. A woman has two X chromosomes; a man has one X chromosome and one Y chromosome. Several traits, including red-green colour blindness, arise from the interaction of genes that are located on the X chromosome. A man…
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sexual differentiation
…one male sex chromosome (the Y chromosome). An egg that has been fertilized has a full complement of 46 chromosomes, of which two are sex chromosomes. Therefore, genetic sex of the individual is determined at the time of fertilization; fertilized eggs containing an XY sex chromosome complement are genetic males,…
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…one male sex chromosome (the Y chromosome). An egg that has been fertilized has a full complement of 46 chromosomes, of which two are sex chromosomes. Therefore, genetic sex of the individual is determined at the time of fertilization; fertilized eggs containing an XY sex chromosome complement are genetic males,…
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genetic testing
Genetic testing and genealogy
…in genealogical genetics analysis include Y chromosome testing, mitochondrial DNA (mtDNA) testing, and detection of ancestry-associated genetic variants that occur as single nucleotide polymorphisms (SNPs) in the human genome. Y chromosome testing is based on genetic comparison of Y chromosomes, from males. Because males with a common male ancestor have…
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…in genealogical genetics analysis include Y chromosome testing, mitochondrial DNA (mtDNA) testing, and detection of ancestry-associated genetic variants that occur as single nucleotide polymorphisms (SNPs) in the human genome. Y chromosome testing is based on genetic comparison of Y chromosomes, from males. Because males with a common male ancestor have…
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