Explanation: When DNA is exposed to UVB radiation, thymine bases that are close to each other in the genetic sequence bond together, and this bond <u>cannot be copied</u> by the enzimes responsible for reproducing the genetic material. In the skin, it causes sunburns and stimulates the production of melanin. Luckily, DNA is only damaged by 0,1% of those UVB radiation photons, but even this percentege is enough to cause a sunburn anyway.