Study UV-Damage

DNA can be broken down by enzyme-catalyzed degradation, which removes nucleotides in a step-wise manner. 

The survival of organisms relies on the accurate transmission of genetic information from one cell to the next, together with the ability to repair DNA damage. To achieve this goal, organisms have developed efficient DNA repair or tolerance mechanisms in order to counteract DNA damage caused by external forces such as UV radiation. 

FIGURE 2.13. Photoproducts (6-4PPs) artd their Dewar valence isomers. 

FIGURE 2.14. Formation of dimers by UV radiation and their photoreactivation by the enzyme photolyase. 

5-deazariboflavin, with absorption maxima of -380 and -440 nm, respectively. One of the chromophores acts as an anteima that absorbs photons and transfers excitation energy to an active cofactor. In the excited state, this cofactor donates an electron to the cyclobutane-pyrimidine dimer (CPD), splitting the cyclobutane ring. The photolyase then exits the DNA, with the efficiency of the photoreactivation process being extremely high. 

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