Regarding double-strand DNA breaks, which statement is true?

Regarding double-strand DNA breaks, which statement is true?

• A. They are the most common form of damage from ionizing radiation
• B. They are easily repaired and usually cause no permanent damage
• C. They are the least common form of damage from ionizing radiation
• D. They do not occur from ionizing radiation

Answer: (C)

Double-strand breaks involve breaks in both strands of the DNA at nearby sites. This kind of lesion is particularly dangerous because it severs both copies of the genetic information, making the integrity of the chromosome uncertain and increasing the risk of chromosomal rearrangements if repaired incorrectly. Ionizing radiation creates many types of damage, and most lesions occur as single-strand breaks or base damage, which are more common than breaks on both strands. Because double-strand breaks require simultaneous hits or very close events on both strands, they happen less frequently, making them among the less common radiation-induced lesions. They are not easily repaired either—cells must use specialized pathways like non-homologous end joining or homologous recombination, and errors during these processes can lead to mutations or cell death. They do occur from ionizing radiation, so the statement that they are the least common form of damage reflects their relative rarity compared with other types of damage, while also acknowledging their high lethality and repair challenges.

Double-strand breaks involve breaks in both strands of the DNA at nearby sites. This kind of lesion is particularly dangerous because it severs both copies of the genetic information, making the integrity of the chromosome uncertain and increasing the risk of chromosomal rearrangements if repaired incorrectly.

Ionizing radiation creates many types of damage, and most lesions occur as single-strand breaks or base damage, which are more common than breaks on both strands. Because double-strand breaks require simultaneous hits or very close events on both strands, they happen less frequently, making them among the less common radiation-induced lesions. They are not easily repaired either—cells must use specialized pathways like non-homologous end joining or homologous recombination, and errors during these processes can lead to mutations or cell death.

They do occur from ionizing radiation, so the statement that they are the least common form of damage reflects their relative rarity compared with other types of damage, while also acknowledging their high lethality and repair challenges.