The information contained in DNA is used by each cell to create the proteins needed for life, which support the cells of the body and help govern cell behavior. Mutations to DNA lead to changes in the proteins the cell produces, which modify the way the cell behaves, and can ultimately lead to diseases such as cancer. Exposure to radiation is considered a mutagen, meaning that it causes mutations in DNA. This is why exposure to radiation increases the risk of cancer. There are many different forms of radiation, which differ in the ways they lead to mutations in cells.
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Effect of UVA Radiation
UVA radiation is released from the sun, and we are exposed to UVA rays as sunlight. UVA rays lead to indirect DNA mutation. Although the rays themselves do not have an effect on the DNA, they lead to changes in the cell that ultimately increase the rate of genetic mutation. UVA works by generating molecules called free radicals within the cells. Free radicals are molecules that are very reactive. They interact with the DNA and interfere with the normal processes that prevent DNA damage, so they ultimately increase DNA mutation.
Exposure to UVA increases an individual's risk for cancer, especially skin cancer. The University of California reports that UVA rays penetrate deep into the skin, and prolonged exposure to this type of radiation leads to skin damage and cancer. Wearing a broad-spectrum sunscreen or sunblock daily protects the skin from UVA rays, decreases the rate of DNA mutation, and helps protect against the development of skin cancers.
Effect of UVB Radiation
UBV radiation is also released from the sun. UVB is the main cause of sunburn and skin cancer, according to the National Outdoor Leadership School. UVB radiation directly damages DNA. It works by promoting the development of cross-links between certain chemicals within DNA, which leads to breaks in the strand of DNA.
When the cell has to repair these breaks, there is an increased risk of mutation due to the possibility of a mistake in the repair. When the cell is exposed to prolonged UVB rays, the millions of resulting DNA breakages result in the development of genetic mutations that can result in cancer. Wearing sunscreen or sunblock protects the skin from UVB radation.
Effect of Ionizing Radiation
Ionizing radiation, the type of radiation released by radioactive materials, also contributes to DNA mutation. Like UVB, ionizing radiation causes direct DNA damage that lead to mutations. Exposure ionizing radiation leads to double-stranded breaks in DNA, so both parts of the DNA molecule are broken at the same spot. This type of breakage is repaired by the cell by reattaching the DNA strands together.
If the cell is exposed to ionizing radiation, double-stranded breaks occur along the entire length of the DNA. Mutations occur if the repair mechanisms re-attach the wrong piece of DNA back together, so that a part of the DNA strand goes missing. This may lead to the deletion of important genes, or a change in the location of a gene within the DNA. These types of mutations are linked to the development of a number of cancers, including leukemia.