How does UVC affect DNA?
Ultraviolet (UV) light kills cells by damaging their DNA. The resulting thymine dimer is very stable, but repair of this kind of DNA damage–usually by excising or removing the two bases and filling in the gaps with new nucleotides–is fairly efficient.
What kind of DNA damage is caused by ultraviolet irradiation?
UV radiation causes two classes of DNA lesions: cyclobutane pyrimidine dimers (CPDs, Figure 1) and 6-4 photoproducts (6-4 PPs, Figure 2). Both of these lesions distort DNA’s structure, introducing bends or kinks and thereby impeding transcription and replication.
What happens to DNA that is exposed to UV radiation?
Direct DNA damage can occur when DNA directly absorbs a UVB photon, or for numerous other reasons. UVB light causes thymine base pairs next to each other in genetic sequences to bond together into pyrimidine dimers, a disruption in the strand, which reproductive enzymes cannot copy.
What is the main damaging effect of UV radiation on DNA?
UVA (and also UVB) radiation cause indirect damage to DNA via absorption of photons by non-DNA chromophores. This generates reactive oxygen species like singlet oxygen or hydrogen peroxide that oxidize the DNA bases causing mutations.
Is UV damage of DNA permanent?
Although the production of dimers on the DNA strand by UV light is common, the natural repair processes of the cell correct most of the distortion they cause quickly enough to avoid permanent damage. Although the natural repair mechanisms are very efficient, dimers can still accumulate, causing cell death or cancer.
How does UV light damage DNA quizlet?
UV light damages the DNA of exposed cells by causing bonds to form between adjacent pyrimidine bases, usually thymines, in DNA chains. The thymine dimers inhibit correct replication of the DNA during reproduction of the cell.
How does UV radiation cause DNA mutation?
UV exposure doesn’t always lead directly to mutations in the DNA. In fact, UV-A radiation commonly causes the creation of a free radical that then interacts with and oxidizes DNA bases. These oxidized bases don’t pair correctly during replication, causing mutations.
Does UV destroy DNA?
One way ultraviolet light can harm cells is by directly damaging DNA. This is something many of us are reminded of every spring and summer – it’s the cause of sunburn! As the name suggests, direct DNA damage occurs when a photon of UV light hits DNA.
Does UV damage DNA?
How do you fix UV damaged DNA?
Because most UV damaged DNA is efficiently repaired by nucleotide excision repair (NER), which is a specialized UV-induced DNA damage repair system, many UV-induced symptoms are closely related to NER. Therefore, understanding the function of NER genes will elucidate the cause of different UV-induced symptoms.
What is the main change produced by UV light in the molecule of DNA?
When UVB light hits the DNA strand, it causes a change in the structure of the chain. The energy of the UVB light alters a chemical bond in the thymine. The altered bond causes the neighboring thymine bases to stick to each other. This pair of stuck-together thymine molecules is called a dimer.
How does UV light cause mutations?