Elements with an unstable nucleus that act as poisons, killing cancer cells without destroying other parts of the body.
An isotope, an atomic form of a chemical element, that is unstable; the nucleus decays spontaneously, giving off detectable particles and energy. radiometric dating A method paleontologists use for determining the ages of rocks and fossils on a scale of absolute time, based on the half-life of radioactive isotopes. reactant A starting material in a chemical reaction. receptor On or in a cell, a specific protein molecule whose shape fits that of a specific molecular messenger, such as a hormone. receptor-mediated endocytosis( en-doh-sy- toh-sis) The movement of specific molecules into a cell by the inward budding of membranous vesicles containing proteins with receptor sites specific to the molecules being taken in; enables a cell to acquire bulk quantities of specific substances.
A form of a molecule that emits radiation. There are three principal type of isotope emitters: alpha, beta, and gamma. Isotopes can be used as diagnostic agents in nuclear medicine. Such agents are chosen because they have an affinity for certain organs or tissues. One can use instruments to detect these isotopes. Brain, bone, liver, and spleen scans are examples of use of isotopes for diagnosis of abnormalities of those organs. Certain radioactive isotopes can damage cancer cells. Physicians use radioactive isotopes to treat cancer in several ways, including attaching the isotope to antibodies made against cancer cell antigens. The antibodies can attach to the cancer cell and the radiation can destroy it and neighboring cells.