Some Questions for Believers ??? Feb 10, 2010 22:22:43 GMT
Post by Al Moritz on Feb 10, 2010 22:22:43 GMT
In other words: "because the non-coding regions show little similarity to chimp sequences and because I don't know the precise function of the RNA transcripts, they must do absolutely nothing". It is precisely this Darwinian mentality that Sternberg said inhibited research in this topic. For under a Darwinian premise, human beings just can't be that different from chimps.
And, as would (or should) be expected, the claim is untrue: we have found functions for many of them. See, e.g., these articles: Non-coding-RNA regulators of RNA polymerase II transcription, 2006 www.nature.com/nrm/journal/v7/n8/abs/nrm1946.html and Small dsRNAs induce transcriptional activation in human cells, 2006 www.pnas.org/content/103/46/17337.abstract . These non-coding RNA (i.e. those that are not translated into protein) have important regulatory functions.
There are some misunderstandings here.
It is a strawman to claim that scientists who consider a lot of DNA 'junk' deny the importance of non-coding regions. In fact, it is consensus among biochemists and biologists that gene regulation is a deciding factor in the differences between species, including the differences between humans and chimpanzees. After all, our cells 'only' express about 20,000 proteins, and we have this in common not just with chimpanzees, but with many other species, down to mice and probably further. And gene-regulation is driven by non-coding regions. So when you say: "For under a Darwinian premise, human beings just can't be that different from chimps", this is patently false.
The fact that many non-coding regions are important, however, does not take away the likelihood that a lot of DNA is in fact 'junk'.
Scientists have deleted up to 1.5 megabase (mb) regions of genes and found no deleterious effect. See:
Nobrega MA et al. 2004. Megabase deletions of gene deserts result in viable mice. Nature 431: 988-993.
A comment is found here:
Given the ludicrous differences in gene sizes between the Viscacha rat and the Brown Norway rat it is belief-defying to uphold the view that all of the extra Viscacha gene is essential.