PseudogenePseudogenes are inactive sequences of genomic DNA which have a similar sequence to known functional genes. Because of this similarity, pseudogenes are normally considered to be evolutionary relatives to normally functioning genes.
Pseudogenes are known to arise via two main processes: duplication and retrotransposition. Most pseudogenes (~80%) develop from retrotransposition which involves the reverse transcription of an mRNA transcript and the subsequent re-integration of a retrotransposon into the genomic DNA.
In the process of duplication, genetic sequences can go through various forms of modification including mutations, frame shifts, insertions and deletions. Significant modification can result in a loss of genetic function, in which case proteins are no longer produced in the transcription and/or translation stages. Typically, non-functionality develops from modifications which effect start codons, stop codons, and other regulatory elements, which are significant in normally functioning genes for conducting transcription.
Mutations in pseudogenes are typically neutral and free from selection because they are normally located in portions of the genome where modifications do not bring aobut a deleterious effect.
Web Resources On Pseudogene
http://individual.utoronto.ca/PBL_pseudogenes/status.htm
http://pseudogene.org/
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