X Chromosome Topics

• y chromosome
• barr body
• base pairs
• determination system
• ccd camera
• sex determination
• dapi
• genetic disorders
• unique properties
• animal species
• human genome
• chromosomes
• fertilization
• building material
• genes
• mutations
• counterpart
• mammals
• nucleus

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X Chromosome, X Chromosome

Bottom: Same nucleus stained with DAPI and recorded with a CCD camera. The Barr body is indicated by the arrow, it identifies the inactive X (Xi). The X chromosome is one of the two sex-determining chromosomes in many animal species, including mammals (the other is the Y chromosome). It is a part of the XY sex-determination system and X0 sex-determination system. The X chromosome was named for its unique properties by early researchers, and this resulted in its counterpart being named the Y chromosome for the next letter in the alphabet when it was discovered later.

The X chromosome spans more than 153 million base pairs (the building material of DNA) and represents about 5% of the total DNA in women's cells, 2.5% in men's.

Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. The X chromosome contains about 2000 genes compared to the Y chromosome containing 78 genes, out of the estimated 20,000 to 25,000 total genes in the human genome. Genetic disorders that are due to mutations in genes on the X chromosome are described as X linked.

As a result, the XX combination after fertilization has the same effect as a XY combination, resulting in a male. However, the other genes of the X chromosome cause feminization as well.

Source: Wikipedia > X Chromosome