AP BIOLOGY

Detailed explanation-1: -Irregular and inadequate use of sunscreen during exposure to UV radiation results in thymine dimer formation, which may lead to mutation and subsequent cancer development.

Detailed explanation-2: -In fact, UV-A radiation commonly damages DNA in an oxygen-dependent manner that involves photosensitization. This leads to the production of a free radical that then interacts with and oxidizes DNA bases. These oxidized bases don’t pair correctly during replication, resulting in mutations (Figure 1).

Detailed explanation-3: -Cyclobuthane thymine dimer is a photolesion produced by UV radiation in sunlight and is considered as a potential factor causing skin cancer.

Detailed explanation-4: -Ultraviolet (UV) light induces specific mutations in the cellular and skin genome such as UV-signature and triplet mutations, the mechanism of which has been thought to involve translesion DNA synthesis (TLS) over UV-induced DNA base damage.