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Definition: x-chromosome from Philip's Encyclopedia

One of the two kinds of sex-determining chromosome; the other is the y-chromosome. In many organisms, including humans, females carry two x-chromosomes in their diploid cell nuclei, while males carry one x- and one y-chromosome. Non-sexual characteristics are also carried on the x-chromosome: for example, the genes for one form of colour blindness and for haemophilia. See also genetics; heredity


X chromosome

From The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide
Larger of the two sex chromosomes in humans and other placental mammals, the smaller being the Y chromosome . In females both the sex chromosomes are the same – two X chromosomes (XX). In males the two are different – one X chromosome and one Y chromosome (XY). As the presence of a specific genes on the Y chromosome determines a person's sex, individuals with a different number of X chromosomes can still be female if they lack this factor. As the X chromosome contains many more genes than the Y chromosome, the phenomenon of sex linkage , that is the gender-specific appearance of an inherited trait, is commonly associated with genes on the X chromosome. As a result of meiosis gametes from a female each contain one X chromosome. However, gametes from a male are of two kinds. Half of the gametes contain an X chromosome and half contain a Y chromosome. If an X-carrying gamete from a male fertilizes a female gamete the result will be a female. If a Y carrying gamete from a male fertilizes a…
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Full text Article X Chromosome

From Brenner's Encyclopedia of Genetics
A Giemsa-banded ideogram of a human X...
Abstract The X chromosome is one of the two sex chromosomes in humans. It is highly conserved among other mammalian species. The X chromosome accounts for about 5% of the total human genome and contains upward of 1200 genes. Many X chromosome genes, about one-fifth, appear to play a role in human…
| 2,182 words , 2 images
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Full text Article X chromosome

From The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide
Larger of the two sex chromosomes in humans and other placental mammals, the smaller being the Y chromosome . In females both the sex chromosomes are the same – two X chromosomes (XX). In males the two are different – one X chromosome and one Y chromosome (XY). As the presence of a specific genes on…
| 394 words
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Full text Article X-Chromosome Inactivation

From Brenner's Encyclopedia of Genetics
X-Chromosome Inactivation
Abstract In female mammals, all X chromosomes except one are transcriptionally inactivated early in embryonic development. This is known as X-chromosome inactivation and is a form of dosage compensation, giving equal dosage of the products of X-linked genes in males and females. The mechanism is of…
| 2,025 words , 1 image
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Full text Article X chromosome

From Collins Dictionary of Medicine
The CHROMOSOME which, with the Y chromosome, determines the sex of the individual. About 50% of sperms carry an X chromosome and 50% a Y. The sex of the future child is determined by whether an X-carrying or a Y-carrying sperm happens to fertilize the ovum. The ovum carries only an X chromosome. …
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Full text Article X Chromosome

From Black's Medical Dictionary, 43rd Edition
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Full text Article X chromosome ‡

From Cambridge Dictionary of Human Biology and Evolution
| 81 words
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Full text Article X chromosome

From The American Heritage Student Science Dictionary
| 26 words
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Full text Article x-chromosome

From Philip's Encyclopedia
| 68 words
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Full text Article X chromosome genes

From Cambridge Dictionary of Human Biology and Evolution
| 35 words
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Full text Article X chromosome inactivation

From Dictionary of Developmental Biology and Embryology
| 22 words
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