Question

Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight. This occurs because their cells have which impaired ability?

- They cannot undergo mitosis.
- They cannot exchange DNA with other cells.
- They cannot replicate DNA.
-They do not recombine homologous chromosomes during meiosis.
-They cannot repair thymine dimers.

Answer 1

Individuals with xeroderma pigmentosum are hypersensitive to sunlight as they cannot repair thymine dimers due to a defect in the nucleotide excision repair mechanism, leading to a higher risk of skin cancer.

Step-by-step explanation:

Individuals with the disorder xeroderma pigmentosum have an impaired ability to repair damage caused by UV light. This hypersensitivity to sunlight occurs because their cells cannot employ the nucleotide excision repair mechanism to fix thymine dimers that form when DNA is exposed to UV radiation. These dimers distort the DNA structure, leading to an inability to replicate DNA properly, and significantly increasing the risk of skin cancer.