One hereditary disease in humans, called xeroderma pigmentosum (XP), makes homozygous individuals exceptionally susceptible to UV-induced mutation damage in the cells of exposed tissue, especially skin. Without extraordinary avoidance of sunlight exposure, patients soon succumb to numerous skin cancers.
-Given the damage caused by UV, the kind of gene affected in those with XP is one whose product is involved with
A) mending of double-strand breaks in the DNA backbone.
B) breakage of cross-strand covalent bonds.
C) the ability to excise single-strand damage and replace it.
D) the removal of double-strand damaged areas.
E) causing affected skin cells to undergo apoptosis.

Question

Quizplus · Accepted Answer

The kind of gene affected in individuals with xeroderma pigmentosum (XP) is involved in excising single-strand damage and replacing it. This is because XP patients are exceptionally susceptible to UV-induced mutation damage in the cells of exposed tissue, especially skin. The product of the affected gene is involved in repairing this kind of damage, which is caused by the excision of nucleotides from the single-strand damaged region and replacement with complementary nucleotides. Without this repair mechanism, patients with XP develop numerous skin cancers.

One Hereditary Disease in Humans, Called Xeroderma Pigmentosum (XP), Makes