Uv light can induce mutations in dna by

Instead, during replication, 8-oxoguanine can base pair with adenine via two hydrogen bonds. When the second strand is synthesized, the base position originally occupied by a guanine is then replaced with a thymine, leading to a G to T transversion. Well, a plasmid that contains UV-induced dimerizing mutations is unlikely to be replicated efficiently in E. The structural change brought about by dimerizing mutations leaves the plasmid DNA available to repair enzymes.

However, errors in repair commonly lead to the replacement of cytosine for thymine, thus changing the original DNA sequence in potentially detrimental ways. Short wavelength UV-B and UV-C light can directly cause dimerization of pyrimidines, and directly prevent replication of plasmid DNA, or induce mutations after faulty repair. Long wavelength UV-A light is generally less directly damaging, and instead causes mutations through the production of reactive oxygen species.

This is why it is best to use a long-wavelength transilluminator to visualize DNA bands, if possible! Hopefully this article has not only taught you the importance of using a broad-spectrum sunscreen, but also taught you the chemistry behind the damaging effects of UV light. Has this helped you? Then please share with your network. USA 84 , — Vrieling, H. Mc Gregor, W. Wehner, J. Mutational specificity at the lacZ gene, J. B: Biol. Amstrong, J. Okaichi, K.

Drobetsky E. USA 92 , — Robert, C. Keyse, S. Frijhoff A. DeMarini, D. Stary, A. Hollstein, M. Negishi, K. Dumaz, N. Carcinogenesis 18 , — USA 93 , — Duman, N. Since 5'-CG sequences are methylated along the p53 coding sequence in human cells, these mutations may be derived from sunlight-induced pyrimidine dimers forming at sequences that contain 5-methylcytosine.

Cyclobutane pyrimidine dimers CPDs form preferentially at dipyrimidines containing 5-methylcytosine when cells are irradiated with UVB or sunlight. In order to define the contribution of 5-methylcytosine to sunlight-induced mutations, the lacI and cII transgenes in mouse fibroblasts were used as mutational targets.