Answer:
UV radiation basically damages skin by transferring energy to molecules in your skin, such as DNA, fat, proteins, etc. These molecules, which are already in their proper arrangement, absorb this energy. If the molecules absorb enough energy, the bonds holding them together can break, forming a new shape completely. For a cell that already has been chugging along smoothly thanks to specific molecules with specific shapes doing specific jobs, this is a big deal and causes serious problems.
Explanation:
UV radiation damage to DNA is a particular problem. DNA is a huge molecule and actually quite fragile. When a molecule of DNA is present in a cell, it resembles a zipper: it has two strands, with each strand tightly bound to corresponding molecules on the opposite side, called bases.