High-energy radiation is often used to treat cancer.The radiation damages the cancerous cells, and the cell cycle checkpoint for DNA repair is overwhelmed.Radiation therefore
A) causes apoptosis when cells are at the S and G2 checkpoints.
B) inhibits the growth factor at the restriction point.
C) blocks DNA replication.
D) causes apoptosis only at the tumor site.
E) kills all tumor cells without harming healthy cells.

Question

Quizplus · Accepted Answer

High-energy radiation overwhelms the cell cycle checkpoint for DNA repair, leading to apoptosis (programmed cell death) of cancerous cells that are at the S and G2 checkpoints. This is because these cells are actively replicating their DNA and are more sensitive to DNA damage caused by radiation. Furthermore, radiation therapy is usually targeted specifically at the tumor site, so it can cause apoptosis only in cancerous cells without significantly harming healthy cells. Therefore, options B, C, and E are incorrect.

High-Energy Radiation Is Often Used to Treat Cancer