While the sheer amount of information that can be stored in genetic code is well known — a single gram of DNA is estimated to be able to hold 700 terabytes of information — it turns out that there is yet another layer of information that is mechanically encoded into our genetic material. A new study has found this extra layer of encoded information in our DNA, in that the way the molecule itself is folded acts as yet another layer of information that can be used by the host organism’s cells. As it is, each cell holds strands of DNA that are approximately six feet long, so each strand needs to be folded extremely tightly to fit into the cell’s microscopic nucleus.
While the DNA in our cells contain the full blueprint that maps out our bodies, not all of it may be needed by the cells that make up a particular organ. The new study, conducted by a research team at Leiden University in the Netherlands, found that the particular way the molecule is folded in each cell allows the individual cell access to the parts of the code that is relevant to that particular organ, and hides information that is unnecessary.
This is a mechanism that biologists have suspected to exist for quite some time, but until now haven’t been able to confirm. The experiment itself involved sophisticated computer models of the genomes of both baker’s yeast and fission yeast. The suspected level of information was randomly assigned to the models, and the mechanical cues resulting from this affected how the simulated DNA expressed the proteins that are used to make up the host cell.
"The mechanics of the DNA structure can change, resulting in different packaging and levels of DNA accessibility," the study explains, "and therefore differing frequency of production of that protein." This discovery may allow researchers to essentially "hide" unwanted portions of DNA code, such as those that cause specific diseases, so they’re not accessible to the patient’s cells, or perhaps to prompt stem cells to grow into specific organs and tissue for replacement.
- By Richard Wheeler (Zephyris) 2007. Image of EcoRV homodimer in complex with a DNA substrate. via Wikimedia Commons
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