A researcher is investigating compounds that modulate the cell cycle as possible chemotherapeutic agents against peripheral T-cell lymphoma. The researcher discovers a group of natural compounds with inhibitory activity against histone deacetylases, a class of enzymes that remove acetyl groups from the lysine residues of histones. A histone deacetylase inhibitor most likely causes which of the following?
APrevention of DNA strand reannealing
BIncreased heterochromatin formation
CSuppression of gene transcription
DRelaxation of DNA coiling
ETighter coiling of DNA
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
An investigator is comparing DNA replication in prokaryotes and eukaryotes. He finds that the entire genome of E. coli (4 × 106 base pairs) is replicated in approximately 30 minutes. A mammalian genome (3 × 109 base pairs) is usually replicated within 3 hours. Which of the following characteristics of eukaryotic DNA replication is the most accurate explanation for this finding?
AReplication inhibition at checkpoint
BAbsence of telomerase enzyme activity
CDNA compaction in chromatin
DSimultaneous replication at multiple origins
EMore efficient DNA polymerase activity
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