In cells that are exposed to sunlight, ultraviolet (UV) light can result in covalent linkage between two adjacent DNA bases. If not repaired in time, such dimers can lead to inheritable mutations. Consider the sequence 5?-GGTATGATCATTATAA-3? in the chromosome of a cell that is exposed to intense sunlight. How many possible dimers can form in the region of DNA double helix corresponding to this sequence?

Question

Quizplus · Accepted Answer

UV irradiation can cause two adjacent pyrimidine bases (T or C) to form these covalent dimers. Please note that the complementary strand should also be taken into account. The possible sites of damage are TC and TT doublets in the strand shown, and TT, TC, and CC doublets in the complementary strand.

In Cells That Are Exposed to Sunlight, Ultraviolet (UV) Light