Why does incubation in the dark versus light affect UV –induced mutagenesis?
Incubation in the dark has no damage in the DNA since there is no absorption of energy to cause changes in atoms, while incubation in Ultraviolet light (UV) is a type of radiation that can damage the DNA. The damage happens because the DNA absorbs energy and causes atoms to behave abnormally and results in the chemical reaction. And this process is called UV mutagenesis. This process causes a powerful mutagen and firstly produces dimers between two neighboring pyrimidine bases on a similar DNA strand. Mutagenesis
There are no effects of mutagenesis in incubation in the dark hence there are is no need for photo reactivation process, and there is no need for high light intensity in the dark while The effects of mutagenesis in UV can be reversed by photo reactivation process, which requires high light intensity. The UV light kills cells by damaging DNA. It achieves in two ways that are practicing or removing the bases and replacing them in the gaps with another new nucleotide. It causes mainly two damages, the first is thymine dimerization, and the second is DNA bonds broken.
There is no need for high light intensity in the dark incubation, while there is a need for high light intensity in the UV incubation for the process of photo reactivation.
There is no induction of mutations in incubation in the dark, while UV light induces some mutations in the skin genome, which includes UV-signal-ture and triplet mutations, the mechanism of which it involves DNA synthesis over UV induced DNA base to destroy.
UV radiation may lead to the formation of free radicals that may come in contact with the adenine of DNA bases. These two adenine bases mismatched accordingly during replication resulting in mutations.