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| Sex is determined by the sex [[Chromosome|chromosomes]] of a particular organism. In humans, females have 2 X chromosomes whilst males have XY chromosomes. The female (in humans and many other mammals) is known as the [[Homogametic|homogametic]] sex, whilst the male is known as the [[Heterogametic|heterogametic]] sex. By contrast some organisms (birds and some reptiles, butterflies and moths) the male is homogametic and the female is heterogametic. In this case the sex chromosomes are represented by WZ (female) and ZZ (male) rather than the XX-XY mechanism.<br>
| | See [[Sex chromosome]] |
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| There are many different disorders and diseases associted with sex chromosomes resulting from [[Non disjunction|non disjunction]] during meiosis:
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| *[[Klinefelter syndrome|Klinefelter syndrome]] is caused by the presence of more than one [[X chromosome|X chromosome]] when a [[Y chromosome|Y chromosome]] is also present (47,XXY). In this case the Y chromosome is enough to determine maleness. They will have 1 barr body in their chromosomes due to the presence of 2X chromosome. However, the affected male will be sterile and may also be affected by other symptoms such as the development of breasts, small external genitalia and testes and also mental impairment. Males affected also tend to be phenotypically tall.
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| *[[Turner syndrome|Turner syndrome]] is caused by [[Monosomy|monosomy]] of the X chromosome (45,X). The affected female will probably not sexually mature properly and will oftern experience spontaneous abortion. Those affected also tend to be [[Phenotype|phenotypically]] short <ref>[Daniel L. Hartl and Elizabeth W. Jones (2009) Genetics analysis of genes and genomes (seventh edition) mississauga, Jones and Bartlett Publishers, Inc.]</ref><ref>Genetics Home Reference, (2014). Klinefelter syndrome. [online] Available at: http://ghr.nlm.nih.gov/condition/klinefelter-syndrome [Accessed 14 Nov. 2014]</ref>.
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| === References ===
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| <references />
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Latest revision as of 18:18, 22 October 2018