How UV Light Damages DNA
The DNA molecule is usually pictured like a twisted ladder with spaces between each pair of bases that form the rungs. In reality, the bases are stacked on top of the other like coins so previous ideas about the interaction of DNA with exposures like ultraviolet (UV) radiation may be flawed.
Bern Kohler and his colleagues at Ohio State University have come up with a new theory of how UV light damages DNA. They report in Nature that UV radiation does not cause mutations by damaging the bonds within the “rungs” of base pairs. Instead, UV energy travels up the side of the DNA molecule’s ladder-like structure.
Here are the steps leading up to DNA damage from the moment sunlight hits our cells:
- As sunlight warms our skin, UV photons are absorbed by the bases, causing their electrons to vibrate.
- High-energy electron vibrations nudge the atoms in the bases around, but only along one edge of the DNA ladder at a time.
- In most cases, DNA returns to normal after the energy wave passes.
- In a minority of cases, the atoms dont return to their original positions, and new chemical bonds are formed.
- The new chemical bonds create “photolesions” that prevent DNA from replicating properly and may lead to cancer and other diseases.
The best way to avoid excessive sun exposure is to stay out of the sun, but that’s obviously not possible unless you live in a cave in which case you should be worrying about vitamin D deficiency. Sunscreens are a good alternative to burrowing underground. Similar to the way DNA disperses the energy absorbed from UV radiation, sunscreen forms a barrier between sunlight and your skin - dissipating UV light either by reflecting it or converting it into heat.
So, to avoid DNA damage via UV radiation, slather it on and cover it up. All within moderation, of course.
Newswise, August 24, 2005
Photo credit: U.S. Department of Energy Human Genome Program
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POSTED IN: General Genetics and Health
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2 opinions for How UV Light Damages DNA
Lene Petite
Jul 25, 2006 at 1:09 am
I know that the sun has different levels of radioactivity from the morning till the evening. Is it equally dangerous to get burnt in different times of the day?
Hsien Hsien Lei, PhD
Jul 27, 2006 at 5:55 am
Lene: Sunburn is damage to your skin and cells which is always bad.
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