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Junk DNA Not Junk After All September 9, 2012

Posted by Metabiological in Genetics.
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A big new study out of the Human Genome Research Group has just been released to the public.  This is probably the biggest study in genetics since the Human Genome project a decade ago and the results coming out seem to be just as fascinating.

“The ENCODE project not only generated an enormous body of data about our genome, but it also analyzed many issues to better understand how the genome functions in different types of cells. These insights from integrative analyses are really stories about how molecular machines interact with each other and work on DNA to produce the proteins and RNAs needed for each cell to function within our bodies,” explains Ross Hardison of Pennsylvania State University, one of the JBC authors…

The human genome consists of about 3 billion DNA base pairs, but only a small percentage of DNA actually codes for proteins. The roles and functions of the remaining genetic information were unclear to scientists and even referred to as “junk DNA.” But the results of the ENCODE project is filling this knowledge gap. The findings revealed that more than 80 percent of the human genome is associated with biological function.

The status of junk DNA has been a thorn in biology’s side for a while now so it’s nice to have that question at least somewhat resolved.  What’s most interesting for me is how this changes our view of the complexity of the human body.

It’s been becoming apparent for some time now that while what genes an organism possess are very important in determining organism functioning how those genes are activated and deactivated is just as (or possibly more) important.  The field of epigenetics has been hot in recent years as scientists have begun to examine how regulation of gene expression rather then the actual structure of DNA determines the phenotype of individuals.  If what this study tells us is correct it would seem that the vast majority of DNA is devoted to this regulation and while I’m not one to say that size always matters the sheer amount of this non-coding DNA speaks volumes about it’s likely importance.

It also makes the job of predicting the development of phenotypes a bit more tricky.  “Junk DNA” may regulate gene expression but many other factors, including environmental, can affect junk DNA.  Furthermore there is some evidence that changes in gene expression can actually be passed on to descendents, a form of non-Darwinian evolution.  Will Lamark make a comeback?  Hard to say but we do seem to be on the edge of a major shift in our understanding of the basics of life.

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