An interesting new paper on how the genetic code minimizes the impact of mistranslations:
Statistical and biochemical studies of the standard genetic code (SGC) have found evidence that the impact of mistranslations is minimized in a way that erroneous codes are either synonymous or code for an amino acid with similar polarity as the originally coded amino acid. It could be quantified that the SGC is optimized to protect this specific chemical property as good as possible. In recent work, it has been speculated that the multilevel optimization of the genetic code stands in the wider context of overlapping codes. This work tries to follow the systematic approach on mistranslations and to extend those analyses to the general effect of frameshift mutations on the polarity conservation of amino acids. We generated one million random codes and compared their average polarity change over all triplets and the whole set of possible frameshift mutations. While the natural code—just as for the point mutations—appears to be competitively robust against frameshift mutations as well, we found that both optimizations appear to be independent of each other. For both, better codes can be found, but it becomes significantly more difficult to find candidates that optimize all of these features—just like the SGC does. We conclude that the SGC is not only very efficient in minimizing the consequences of mistranslations, but rather optimized in amino acid polarity conservation for all three effects of code alteration, namely translational errors, point and frameshift mutations. In other words, our result demonstrates that the SGC appears to be much more than just “one in a million”.
Abstract: (open access) – Geyer R, Madany Mamlouk A. (2018) On the efficiency of the genetic code after frameshift mutations. PeerJ 6:e4825 https://doi.org/10.7717/peerj.4825 More.
The researchers conclude:
For all three deleterious mechanisms, the genetic code shows clear evidence of its capability to minimize their effects by conserving the polarity of the coded amino acids. The results show that the SGC is most efficient in minimizing the effect of translational errors. It outperforms more than 99.99% of one million randomly generated codes. This effect even got stronger for the combination of all three proposed measures, indicating that all three factors might have been contributed independently to the evolution of this sophisticated, robust, and universal coding. … Thus, our principal conclusion is that stability against frameshift mutations should be put on to the list of the series of features the SGC achieved in the course of evolution.
“Optimized”?“Achieved”? This is the language of design and purpose. No assertion is made here that the genome is a random concoction of chemicals that somehow swished together.
Hat tip: Pos-darwinista
See also: Decidedly un-Darwinian admissions re proteins. What is killing Darwinism is really that we are seeing a fascinating new world of biology and it is just not the textbook Darwinism defended in so much popular media. And whatever it turns out to be, it will never be that.