Cancer cells are more easily damaged by radiation than normal cells because they are -
A
Undergoing rapid division
B
Different in structure
C
Non-dividing
D
Starved of mutation
The answer is A.
Solution
Cancer cells have lost the normal controls on cell division (contact inhibition), so they divide rapidly and continuously. Cells are most sensitive to radiation while they are dividing, because their DNA is being replicated and the chromosomes are condensing; radiation damage to DNA at this time stops division and kills the cell. So radiotherapy damages rapidly dividing cancer cells more than normal cells, most of which divide slowly or not at all. (This is also why rapidly dividing normal cells, such as those of hair follicles and bone marrow, are affected during radiotherapy.) So cancer cells are more easily damaged by radiation because they are undergoing rapid division.
ConceptRadiosensitivity of dividing cells
Human Health and Disease in past papers
121 questions from this chapter have appeared across 27 exam years.
