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Genetic Code variations (was Re: Dino-fuzz found in amber?)



> > Additionally, the "genetic code" mapping 64 codons to
> 20 amino acids is not uniform in life - there are variations
> of it
> 
> Didn't know that! Where can we read more about that?
> -- 
> T. Michael Keesey

Mycoplasma has many variation and doesn't even use all 64 codons.
One codon will stall the ribosomes if it is produced by mutation

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC50926/
http://www.ncbi.nlm.nih.gov/pubmed/2478713
http://www.ncbi.nlm.nih.gov/pubmed/3936937?log$=activity
http://www.ncbi.nlm.nih.gov/pubmed/2253708?log$=activity


For a pretty complete list, you can look at this page:
http://www.ncbi.nlm.nih.gov/Taxonomy/Utils/wprintgc.cgi?mode=t#SG5
Note that the mitochondrial codes often contain many variations.

I don't think that page includes the rare case of organisms using more than 21 
amino acids.

http://www.ncbi.nlm.nih.gov/pubmed/16256420
"The direct genetic encoding of pyrrolysine."

Selenocystine is another example, but this amino acid is not directly encoded 
(it is instead produced by modification of cystines).


Anyway, hopefully this is enough to satisfy your curiosity, or set you on the 
right path if you are still curious about genetic code variations.

I'm fairly sure the code is uniform within the vertebrate nuclear genomes, but 
there are many variations within even metazoans, and obviously even more so in 
Eukaryotes/the entire "web/tree of life".