the DNA double helix.
DNA employs some chemical reactions of its own to heal itself. But when DNA sustains too much damage, it can't replicate properly. Badly damaged cells simply die -- the effect that gives sunburn its sting. Scientists also believe that chronic damage creates mutations that lead to diseases such as skin cancer.
For this study, the chemists used a technique called transient absorption to observe the DNA damage. Transient absorption is based on the idea that molecules absorb light at specific wavelengths, and it allows researchers to study events that happen in less than a picosecond.
They took specially designed strands of DNA -- ones made solely of thymine bases, in order to boost the chance of observing a reaction between adjacent thymines -- and exposed them to UV light. Then they timed the reactions that caused the new thymine bonds to form.
Kohler stressed that he and his colleagues examined damage to isolated DNA strands, not DNA within a cell. Sunburn results from a series of chemical reactions in a living cell, and so this experiment did not allow them to see a cell sustain sunburn.
This is, however, the first time anyone has observed the initial molecular events behind damage to DNA. Kohler thinks the results might make scientists attack the problem of UV damage in a new way.
DNA in a cell is always moving, he explained. It bends and twists one way or another because it is a relatively flexible molecule. This flexibility enables the normal chemical reactions that are constantly happening in the cell. Each shape-shift can require anywhere from a few to several hundred picoseconds to complete.
That's fast, but this new study shows that UV damage happens many times faster. On the timescale that the unwanted bonds form, even a rapidly moving DNA molecule would essentially appear frozen.
That means that whether or not two thymine bases are damaged depends on the po
'"/>
Source:Ohio State University
Related biology news :
1. Scientists ID molecular switch in liver that triggers harmful effects of saturated and trans fats
2. Scientists Replicate Hepatitis C Virus in Laboratory
3. Scientists detect probable genetic cause of some Parkinsons disease cases
4. Scientists find missing enzyme for tuberculosis iron scavenging pathway
5. Scientists seek answers on what activates deadly anthrax spores
6. Yale Scientists Find MicroRNA Regulates Ras Cancer Gene
7. Scientists collaborate to assess health of global environment
8. Scientists decipher genome of fungus that can cause life-threatening infections
9. Scientists discover the cellular roots of graying hair
10. Scientists rid stem cell culture of key animal cells
11. Scientists develop new color-coded test for protein folding
| Copyright © 2003-2012 Bio-Medicine. All rights reserved. ABOUT | CONTACT US | DISCLAIMER | PRIVACY POLICY | TERMS AND CONDITIONS |  |