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Ultraviolet (UV) rays 79

UV rays can damage DNA, RNA (DNA’s messenger) and proteins. Ultraviolet radiation emitted by the sun is classified into three types of rays: UVA rays, whose wavelength is between 400 and 315 nanometers, UVB rays, between 315 and 280 nanometers, and UVC rays, between 280 and 100 nanometers. A large part of UVB rays is filtered out by the atmosphere, whereas UVC rays are entirely absorbed by the ozone layer and never reach the earth’s surface. The solar radiation to which we are exposed is therefore made up of 95% of UVA rays and 5% of UVB rays.

How does UV radiation interact with DNA? We know that UVB rays chemically alter bases, in particular thymine. The genes which the DNA carries are thereby modified. This chemical reaction explains the strongly mutagenic properties of UVB rays. So for now, exercise caution when out in the sun, as even the 95% of UVA rays, which until recently were still considered harmless, have turned out to be harmful for genes. Let’s not even mention tanning salons, where the ratio of UVA rays is even greater…

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