ABSTRACT
Maintenance of the native DNA sequence and structure is essential for normal function and ultimately to survival. DNA damage can result from numerous external agents and from normal cellular processes. For example, ionizing radiation can induce single-and double-strand breaks, exposure to UV light can produce pyrimidine dimers, spontaneous depurination or enzyme-mediated base removal can produce abasic sites, and cytosine deamination can yield a non-native DNA base-uracil. These lesions produce structural and dynamic changes in DNA, which impair its function. In fact, failure to correctly repair DNA damage can result in mutations, cancer, and death. To minimize the detrimental effects of DNA damage, evolution has provided cells with DNA repair systems, each eliminating a different kind of DNA damage and restoring its normal function.
