Changes

** DNA intercalating agents (e.g. [[ethidium bromide]])

** DNA intercalating agents (e.g. [[ethidium bromide]])

** [[DNA crosslinker]] (e.g. [[platinum]])

** [[DNA crosslinker]] (e.g. [[platinum]])

** Oxidative damage caused by [[oxygen]](O)] [[Radical (chemistry)|radical]]s

** Oxidative damage caused by [[oxygen]](O)] [[Radical (Chemistry)|radical]]s

* Radiation

* Radiation

** [[Ultraviolet]] radiation (nonionizing radiation) - excites electrons to a higher energy level. DNA absorbs one form, ultraviolet light. Two nucleotide bases in DNA - cytosine and thymine-are most vulnerable to excitation that can change base-pairing properties. UV light can induce adjacent thymine bases in a DNA strand to pair with each other, as a bulky dimer.  

** [[Ultraviolet]] radiation (nonionizing radiation) - excites electrons to a higher energy level. DNA absorbs one form, ultraviolet light. Two nucleotide bases in DNA - cytosine and thymine-are most vulnerable to excitation that can change base-pairing properties. UV light can induce adjacent thymine bases in a DNA strand to pair with each other, as a bulky dimer.