Radiation Biology for Physical Scientists/Cell Response to Radiation Mutagenesis

Radiation Induced Damage and Repair Mathematics of Radiation Biology If the mutations in cells are not repaired then the cells die or survive with the mutations. thumb|Human liver with metastatic lesions Cell death Cell death of non-proliferating (static) cells is defined as the loss of a specific function, while for stem cells and other cells capable of many divisions it is defined as the loss of reproductive integrity (reproductive death). The cell commits a pre-programmed suicide called 'apoptosis' before or after it divides or dies when attempting mitosis. Division delay The cell is arrested and repaired in the late G2 phase by the p53 checkpoint gene prior to mitosis. Malignant Transformation The cell survives with mutations that activates the loss of the function of gene groups for tumor suppressions, as well as, DNA stability and gain in the function of gene groups for proliferation - oncogenes. These series of events could lead to the progression of cancer. Foetal Effects Ionizing radiation can produce adverse pregnancy outcomes depending on the stage of gestation at the time of exposure. In utero radiation exposure is particularly harmful during the period of organogenesis during early gestation and 2nd trimester. Examples of radiation effects include intrauterine death, anencephaly, microcephaly and mental retardation. Genetic Effects The mutation stays dormant then appears as hereditary effects. This usually has a time line of generations. Adaptation The irradiated cell is stimulated to react and become more resistant to subsequent irradiation.