It's the inside that counts. Well, an 8.2% portion of the DNA in the body at least.
A study by researchers from the Oxford University shows that no more than 8.2% of human genetic information control what's happening in the body. Out of this figure, a little over a percent is responsible for proteins that handle biological processes while the remaining 7 percent is tasked with turning protein-encoding genes on and off.
It is common knowledge that DNA is important to the body and with that comes the assumption that all of it is has a specific purpose. According to the study, that is wrong, because only a tiny fraction of it actually does anything.
'We found that 8.2% of our human genome is functional. We cannot tell where every bit of the 8.2% of functional DNA is in our genomes, but our approach is largely free from assumptions or hypotheses. For example, it is not dependent on what we know about the genome or what particular experiments are used to identify biological function," said Dr. Gerton Lunter, one of the study's authors.
Using a computational approach, the researchers were able to compare DNA sequences of different mammals, including humans, horses, dogs, rabbits, guinea pigs and mice. Mutations arise due to evolution because it is the body's way of retaining useful sequences in DNA. Researchers were able to observe this by checking DNA deletions and insertions in genomes. And while the study was not being able to specify where the 8.2% is located exactly, it was able to determine at least that functional DNA are not equally important.
The remaining part of the genome is considered to be leftover evolutionary material, more commonly referred to as junk DNA. But even when not useful, the rest of the genome deemed as junk can't just be disregarded either, according to Manolis Kellis, an MIT computational biologist not connected with the study. "We've evolved and that's a messy process. This other DNA really is just filler. It's not garbage. It might come in useful one day. But it's not a burden," adds Lunter.
The study was made possible by funding from the UK Medical Research Council and the Wellcome Trust. Aside from Lunter, the study was authored by Chris Rands, Stephen Meader and Chris Ponting. The researchers came from Oxford University's Department of Physiology (MRC Functional Genomics Unit) and the Wellcome Trust Centre for Human Genetics.