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With few exceptions, all known forms of life on our planet rely on the same genetic code to specify the amino acid composition of proteins. Although different hypotheses abound, just how individual amino acids were assigned to specific three-letter combinations or codons during the evolution of the genetic code is still subject to speculation.


Taking their hints from relics of this evolution left behind in modern cells, researchers at the Salk Institute for Biological Studies concluded that after only two waves of "matching" and some last minute fiddling, all 20 commonly used amino acids were firmly linked with their respective codons, setting the stage for the emergence of proteins with unique, defined sequences and properties.


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"Although different algorithms, or codes, were likely tested during a long period of chemical evolution, the modern code proved so robust that, once it was established, it gave birth to the entire tree of life," says the study's lead author Lei Wang, Ph.D., an assistant professor in the Chemical Biology and Proteomics Laboratory.

"But the universality of the code makes it very hard for researchers to study its formation since there are no organisms using a primitive or intermediate genetic code that we could analyze for comparison," he explains.


Uit: http://www.sciencedaily.com/releases/2010/...00412151823.htm