Why is DNA damage in skin cells from exposure to excessive UV light not completely reversed by photoreactivation?
A)DNA photolyase in humans is activated only under conditions of heat shock.
B)Humans lack a photoreactivation repair mechanism.
C)The presence of histones greatly slows photoreactivation,thus humans depends primarily on other forms of DNA repair.
D)Photoreactivation is specific for the removal of thymine dimers.Thymine dimers do not form in human DNA.

Question

Quizplus · Accepted Answer

Humans lack a photoreactivation repair mechanism, which is why DNA damage in skin cells from exposure to excessive UV light is not completely reversed by this process. Other organisms have enzymes that can directly reverse UV-induced damage using light energy, but humans primarily rely on nucleotide excision repair to remove UV-induced DNA damage.

Why Is DNA Damage in Skin Cells from Exposure to Excessive