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Photolyase is particularly important in repairing UV induced damage in plants. The photolyase mechanism is no longer working in humans and other placental mammals who instead rely on the less efficient nucleotide excision repair mechanism , although they do retain many cryptochromes . [ 11 ]
These reactive chemical species can reach DNA by diffusion and the bimolecular reaction damages the DNA (oxidative stress). Unlike direct DNA damage which causes sunburn, indirect DNA damage does not result in any warning signal or pain in the human body. The bimolecular reactions that cause the indirect DNA damage are illustrated in the figure:
Nucleotide excision repair (NER) is a particularly important excision mechanism that removes DNA damage induced by ultraviolet light (UV). UV DNA damage results in bulky DNA adducts — these adducts are mostly thymine dimers and 6,4-photoproducts. Recognition of the damage leads to removal of a short single-stranded DNA segment that contains ...
This process of absorption works to reduce the risk of DNA damage and the formation of pyrimidine dimers. UVA light makes up 95% of the UV light that reaches earth, whereas UVB light makes up only about 5%. UVB light is the form of UV light that is responsible for tanning and burning. Sunscreens work to protect from both UVA and UVB rays.
UV damage to the DNA sample can reduce the efficiency of subsequent manipulation of the sample, such as ligation and cloning. Shorter wavelength UV radiations (302 or 312 nm) cause greater damage, for example exposure for as little as 45 seconds can significantly reduce transformation efficiency. Therefore if the DNA is to be use for downstream ...
Mutation and DNA damage are the two major types of errors that occur in DNA, but they are fundamentally different. DNA damage is a physical alteration in the DNA structure, such as a single or double strand break, a modified guanosine residue in DNA such as 8-hydroxydeoxyguanosine, or a polycyclic aromatic hydrocarbon adduct. DNA damages can be ...
UV-DDB is not only responsible for the repair of damaged DNA, it can also function by acting as a damage sensor. [5] In base excision repair, UV-DDB galvanizes OGG1 and APE 1 activities. [5] During DNA damage, proteins OGG1 and APE 1 encounter difficulty in repairing the lesions in a DNA wrapped nucleosome.
The rate of DNA repair depends on various factors, including the cell type, the age of the cell, and the extracellular environment. A cell that has accumulated a large amount of DNA damage or can no longer effectively repair its DNA may enter one of three possible states: an irreversible state of dormancy, known as senescence