I'm not one to halve bunnies, so I'm glad I don't have that problem here. You two are somewhat ambiguous, so I guess I'll just have to wade in here. =o)
The Alchemist: You need to extricate the concept of gene duplication from that of pseudogene formation. And in no sense of the word do diploid/polyploid organisms have pseudogenomes! - (nominally) all the genes on all chromosomes are functional, aren't they?
ariels: I'm assuming you mean 'transcribed' rather than 'functional', no? But pseudogenes may or may not be transcribed; that per sé is not an identification criterion, though the inherent inability of the gene to be transcribed does mark it as such. Short range transcriptional control - ie. promoters - are the order of the day here.
Just so we're absolutely clear: pseudogenes are 'genes that aren't genes'. They are not expressed to give functional protein but they do have sequence characteristics of genes (and are in this manner identified via DNA sequencing). Pseudogenes fall into two classes:
These possess the same intron
structure as the related functional gene BUT mutation
s prevent expression
. 'Dead genes' arise as a result of conventional gene duplication
, and are thus often physically close to the live gene.
Example: human pseudo-beta globin.
These are intron-less and promoter
-less versions of functional genes. Processed pseudogenes are thought to arise by integration
of the retrotranscribed
(by the RT
-type elements) mRNA
back into the genome; correspondingly, these can be found anywhere in the genome w.r.t.
the progenitor gene - even on a different chromosome
Example: murine (mouse) pseudo-alpha globin.