Photo by V. Miller
June 8, 2005
UV Light and DNA
Do Different Wavelengths of UV Light Affect DNA Differently?
Janet Song, 12, Audubon, Pa.
Finalist, Discovery Channel Young Scientist Challenge, 2004
Project background: Janet's father, an oncologist, intrigued her by describing how cells become cancerous. She knew that ultraviolet light could damage DNA and eventually cause skin cancer. She wanted to know if different wavelengths of UV light impacted the severity of damage to DNA.
Tactics and results: Janet inserted the gene for resistance to ampicillin into circles of DNA called plasmids. She exposed the plasmids to various wavelengths of UV light. She then inserted the plasmids into E. coli bacteria. If the gene had been damaged, the bacteria would not be resistant to ampicillin. By growing the bacteria in the presence of ampicillin, she could determine if the gene had been damaged or not.
Janet found that UV light with a wavelength of 254 nanometers destroyed 99.9 percent of E. coli colonies within 1 minute. But UV light of 366 nanometers did not lead to the destruction of any E. coli colonies, even after 10 minutes. She concluded that UV wavelength is a key factor in how much DNA damage UV light inflicts.
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