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The X chromosome in humans spans more than 153 million base pairs (the building material of DNA ). It represents about 800 protein-coding genes compared to the Y chromosome containing about 70 genes, out of 20,000–25,000 total genes in the human genome. Each person usually has one pair of sex chromosomes in each cell.
In most mammals, females are XX, and can pass along either of their Xs; since males are XY they can pass along either an X or a Y. Females in such species receive an X chromosome from each parent while males receive an X chromosome from their mother
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What is the X chromosome?
Which chromosome is a part of the XY sex-determination system?
Which chromosome does a male XX pass along?
Who discovered the chromosomal XY sex-determination system?
In most species with XY sex determination, an organism must have at least one X chromosome in order to survive. [3] [4] The XY system contrasts in several ways with the ZW sex-determination system found in birds, some insects, many reptiles, and various other animals, in which the heterogametic sex is female.
The XX/XY sex-determination system is the most familiar, as it is found in humans. The XX/XY system is found in most other mammals, as well as some insects. In this system, females have two of the same kind of sex chromosome (XX), while males have two distinct sex chromosomes (XY).
Overview. Timing. Inheritance of inactivation status across cell generations. Selection of one active X chromosome. Expression of X-linked disorders in heterozygous females. Chromosomal component. Xist and Tsix RNAs. Silencing. Barr bodies. Expressed genes on the inactive X chromosome. Uses in experimental biology. History. See also. References.
A chromosome is a package of DNA with 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.
Turner syndrome ( TS ), also known as 45,X, or 45,X0, is a genetic disorder in which a person's cells have only one X chromosome or are partially missing an X chromosome ( sex chromosome monosomy ). [2] [6] Most people have two sex chromosomes (XX or XY).
