Changes

'''Pseudogenes''' are genes present in an organism's [[genome]] that have lost the ability to code for proteins due to mutation. <ref name=petrov>Petrov, D.A, Hartl, D.L. (2000). Pseudogene evolution and natural selection for a compact genome. The American Genetic Association 91:221-227. [http://www.stanford.edu/group/petrov/research/16.pdf]</ref> They were first identified and dubbed in the late 1970s when researchers began finding non-coding regions in some organisms that were similar to actual coding genes in other organisms. <ref name=sciam>Gerstein, M, Zheng, D. (2006). The real life of pseudogenes. Scientific American 95:48-55. [http://papers.gersteinlab.org/e-print/sciam2/preprint.pdf]</ref> So far an estimated 19,000 pseudogenes have been identified in the human genome, this is almost equal to the total number of coding genes (21,000). <ref name=sciam />  Humans have many pseudogenes including [[L-gulonolactone oxidase]] which is used to synthesize vitamin c.  

'''Pseudogenes''' are genes present in an organism's [[genome]] that have lost the ability to code for proteins due to mutation. <ref name=petrov>Petrov, D.A, Hartl, D.L. (2000). Pseudogene evolution and natural selection for a compact genome. The American Genetic Association 91:221-227. [http://www.stanford.edu/group/petrov/research/16.pdf]</ref> They were first identified and dubbed in the late 1970s when researchers began finding non-coding regions in some organisms that were similar to actual coding genes in other organisms. <ref name=sciam>Gerstein, M, Zheng, D. (2006). The real life of pseudogenes. Scientific American 95:48-55. [http://papers.gersteinlab.org/e-print/sciam2/preprint.pdf]</ref> So far an estimated 19,000 pseudogenes have been identified in the human genome, this is almost equal to the total number of coding genes (21,000). <ref name=sciam />  Humans have many pseudogenes including [[L-gulonolactone oxidase]] which is used to synthesize vitamin c. Research reports that this gene was inactivated in the common ancestor of all [[simians]]. <ref>http://www.cast.uark.edu/local/icaes/conferences/wburg/posters/kmilton/kmilton.html</ref>

==Finding pseudogenes==

==Finding pseudogenes==

Since all pseudogenes are asserted to be descended from a functioning gene the first step is to find the parent gene that it descended from. This is done by using computer programs to compare sequences of DNA across species. <ref name=sciam /> This is a large computational problem but by keeping in mind the phylogenetic relationships between species the search time can be decreased by looking at species that share a more recent common ancestor.<ref name=mito>Bensasson, D., Zhang, D., Hartl, D., Hewitt, G. (2001). Mitochondrial pseudogense: evolution's misplaced witness. Trends in Ecology and Evolution 16: 314-321. [http://www.ioz.ac.cn/department/agripest/group/zhangdx/ZDX-s-pdf%5CTREE2001-Updated_numt.PDF]</ref>  Once a functioning copy of a gene is detected its sequence is compared to the pseudogene. A high correlation in base pairs is used to assign homology. Non-functionality can be demonstrated by attempting to transcribe the sequence in-vitro. <ref name=sciam />

Since all pseudogenes are asserted to be descended from a functioning gene the first step is to find the parent gene that it descended from. This is done by using computer programs to compare sequences of DNA across species. <ref name=sciam /> This is a large computational problem but by keeping in mind the phylogenetic relationships between species the search time can be decreased by looking at species that share a more recent common ancestor.<ref name=mito>Bensasson, D., Zhang, D., Hartl, D., Hewitt, G. (2001). Mitochondrial pseudogense: evolution's misplaced witness. Trends in Ecology and Evolution 16: 314-321. [http://www.ioz.ac.cn/department/agripest/group/zhangdx/ZDX-s-pdf%5CTREE2001-Updated_numt.PDF]</ref>  Once a functioning copy of a gene is detected its sequence is compared to the pseudogene. A high correlation in base pairs is used to assign homology. Non-functionality can be demonstrated by attempting to transcribe the sequence in-vitro. <ref name=sciam />

==See also==

==See also==