Scientists recently reported in Cell that DNA's sequence causes it to be coiled and uncoiled much like a yoyo. "We discovered this interesting physics of DNA that its
sequence determines the flexibility and thus the stability of the DNA package
inside the cell," said Gutgsell Professor of Physics Taekjip Ha, who is a
member of the Carl R. Woese Institute for Genomic Biology at the University of
Illinois. He goes on to say how many people thought this should have been known decades ago but that there are still surprises in the physics of DNA being discovered.
We know that a string of DNA is coiled around histones to create nucleosomes. Then these nucleosomes are braided together into strings that are woven into chromosomes. Scientists assumed that when DNA was uncoiled from these nucleosomes that the two ends were symmetric, meaning that the DNA would uncoil like the untying of a shoe. However, University of Illinois researchers found that DNA is actually asymmetric, making it like the string wrapped around a yoyo. Pulling one end of the DNA would tighten the coil while pulling the other would cause it to uncoil like a yoyo.
The physics of this nucleosome packaging is determined by
the DNA's sequence which makes the strand of DNA flexible enough to be stable to
compact DNA and dynamic so the strand can be uncoiled and read to make
proteins. The research showed that it is easier for the cell's
protein making machinery to read from the "weak" end of the
nucleosome that uncoils more easily. It is now thought that genetic mutations
related to diseases, like cancer, alter the stability of the nucleosome. Professor Ha now plans to use next generation sequencing to determine
the flexibility of an entire genome and hopes to create the first genome-wide
map of physical properties.
I thought this information was very interesting to learn since it seems like something that we should have known for a much longer time with the technology we have available today. Also, this shows how their is always evolving information just waiting to be discovered. Furthermore, I think that by developing a way to make certain strands of harmful DNA the "stronger" end, so that the "weaker" end is coded, we could possibly stop certain diseases.
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