Final answer:
True, prolonged exposure to sunlight can cause thymine dimerization, a form of DNA damage where adjacent thymine bases bond together after absorbing UV light, potentially leading to mutations and cellular damage, but this can often be repaired by nucleotide excision.
Step-by-step explanation:
Prolonged exposure to sunlight can indeed cause thymine dimerization. Thymine dimers are a type of DNA damage that occurs when two adjacent thymine bases on a DNA strand bond together after absorbing ultraviolet (UV) light. This dimerization can interfere with DNA replication and transcription, leading to mutations and cellular damage. For example, the condition known as Xeroderma pigmentosum occurs when the body's ability to repair thymine dimers induced by exposure to UV light is deficient, resulting in skin lesions. However, such damage can often be repaired through a cellular process called nucleotide excision, which helps maintain genome integrity.