Cis
From Free net encyclopedia
- This article is about uses of the word "cis"; for the abbreviation "CIS" see CIS.
Cis is a Latin word meaning "on the same side [of]" and is the opposite of trans. Its uses include:
Image:Cis bond.png Image:Cisbond.JPG
- In chemistry, a double bond (or ring) in which the greater radical on both ends is on the same side of the bond (or face of the ring) is called cis. Compare with trans. In the example shown on the right, both hydrogen atoms, (and both fluorine atoms) are on the same side of the carbon chain. As the carbons are joined by a double bond, these cannot rotate around the molecule. See also Geometric isomerism.
- In genetics, cis- is a prefix used in terms such as "cis-regulation" to signify the co-location of two or more genes on the same chromosome of a homologous pair. The action of molecules is also described in these terms (see Cis-acting).
- In geography, placenames beginning with Cis- convey the meaning "on this side of". Examples include Ciskei (referring to the Kei River), Cisleithania (Leitha), Cisalpine Gaul (Alps), Cisjordan (Jordan River). The antonym is Trans-.
- In astronomy cislunar means outer space between the Earth and the Moon. Translunar is its antonym.
- In medicine and sociology, Cisgender and cissexual are the opposite of Transgender and transsexual, respectively. Both describe people whose gender identity matches their physical and/or assigned sex.
Other meanings of cis, not related to the Latin term, are:
- In mathematics, r cis θ is a now rarely used abbreviation for r(cos θ + i sin θ), which is equal to r(eiθ) (see Euler's formula).
For uses as an acronym, see CIS.