A 23-year-old woman is brought to the emergency department 30 minutes after stepping on a piece of broken glass. Physical examination shows a 3-cm, ragged laceration on the plantar aspect of the left foot. The physician uses hydrogen peroxide to clean the wound. Which of the following is the most likely mechanism of action of this disinfectant?
AFormation of free radicals
BIntercalation of DNA
CCrosslinking of proteins
DHalogenation of nucleic acids
ECongealing of cytoplasm
A 17-year-old patient presents to the emergency department with left wrist pain after falling off of his bike and landing on his left hand. On physical exam the thenar eminence is red, swollen, and tender to palpation, so a radiograph is ordered. The patient is worried because he learned in biology class that radiography can cause cancer through damaging DNA but the physician reassures him that radiographs give a very minor dose of radiation. What is the most common mechanism by which ionizing radiation damages DNA?
AStrand breakage
BThymidine dimer formation
CMicrosatellite instability
DCyclobutane pyrimidine dimer formation
ECytosine deamination
A 3-year-old male child is found to have a disease involving DNA repair. Specifically, he is found to have a defect in the endonucleases involved in the nucleotide excision repair of pyrimidine dimers. Which of the following is a unique late-stage complication of this child's disease?
ATelangiectasia
BColorectal cancer
CMalignant melanoma
DLymphomas
EEndometrial cancer
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