How does ionized radiation induce chromosome damage?

Answer 1

There are two models, essentially, that radiobiologists use to explain this phenomena of ionizing radiation damage to cells. One is direct target theory, which explains both chromosome damage and cell death, the other is indirect action, which is associated more with cell death. Direct target theory assumes that the ionizing radiation interacts with the cellular macromolecule, such as DNA or RNA, breaking the electron bonds (hence, ionizing), and causing disruption or change in the biologic function of that molecule. Sometimes this damage can be repaired, sometimes the damage is fatal to the cell. If the ionizing occurs in the DNA molecule, which is the structural component of the chromosome, the damage may change the chromosomal function, and if the cell lives, may be passed on to the offspring as genetic mutation. Please note however that any observed mutations are the same mutations one would see in the population naturally. Unlike the movies, radiation induced mutations aren't determined by the type of mutation, but determined by the occurance of exposure to radiation. Indirect action occurs when the water in the cell is ionized, creating free radicals, which further create hydrogen peroxide and oxygen in the cell. This chemical molecule in the cell typically kills the cell. Of the two methods of interaction, the indirect method is thought to occur most often. Gregory G. Passmore, Ph.D., CNMT