What is Allele frequency?
'''Allele frequency''' refers to the different forms of a [[gene]] at a single position on a [[chromosome]]. It is the proportion of a given [[allele]] to all alleles at the same [[locus]].<ref>King R.C. Stansfield W.D. & Mulligan P.K. 2006. ''A dictionary of genetics'', 7th ed. Oxford. p16</ref><ref>Klug W.S; Cummings M.R; Spencer C.A. & Palladino M.A. ''Concepts of Genetics''. 10th ed, Pearson. p700{{ndash}}706, including worked examples.</ref> It is usually expressed as a [[percentage]]. Allele frequencies may be used to describe [[genetics|genetic]] diversity in a [[population]]. If the frequency of any allele is above 1% it is probable that [[natural selection]] is maintaining it at this level. This is because the natural [[mutation]] rate of an allele is almost always much lower than 1%. A '''fixed allele''' is one allele that exists for a particular population. A fixed allele is [[homozygous]] for all members of the population.<ref>{{cite web|url=http://groups.molbiosci.northwestern.edu/holmgren/Glossary/Definitions/Def-F/fixed_allele.html|title=fixed allele definition|website=groups.molbiosci.northwestern.edu}}</ref> The term ''allele'' refers to one variant gene out of several possible for a particular locus in the DNA. When all but one allele go away, one only remains. That allele is said to be fixed. == References == {{Reflist}} {{biology-stub}} [[Category:Classical genetics]]