Radioactive Tagging
Radioactive tagging is a process in which a regular isotope of an element is replaced by a radioactive isotope of the same element in order to track the presence and concentration of that element in a biological sample. This has applications in fields such as of biology by allowing biologists to track biological processes, and in medicine, by allowing doctors to track movement of particles throughout the body. Using imaging devices, doctors can then see things such as blood clots and tumors through radioactive tagging.
For example, regular nitrogen can be replaced by a radioactive isotope of nitrogen in a sample, such as DNA, and then this sample can be left to replicate in an environment lacking these radioactive tags. The DNA is then radioactively tagged because it's nitrogenous bases have been replaced with radioactive isotopes. Subsequent generations of DNA replication can be evaluated based on their radioactivity; the more radioactive a generation, the more of the original DNA sample is present in it. A similar method, using isotropic tagging based on different molecular weights instead of radioactivity, was used to determine that DNA replication was semi-conservative. The method of radioactive tagging can be used to track the movement and distribution of molecules throughout biological reactions and processes.
Another application of radioactive tagging is following a biological process happening in vivo, such as cellular respiration. If a glucose molecule is radioactively tagged using radioactive carbon, the molecule can be tracked throughout the process of glycolysis and it's breakdown into pyruvate, and tracked through the rest of the cycle until it is expelled as carbon dioxide. This method of tracking is very simple, needing only a radioactive isotope to introduce into the biological system, and a device to track the movement of the radioactive molecule throughout the body.
Usage of this method in live humans and other animals is relatively safe because the radioactive tags are used in small enough quantities to not cause harm to the organism, but large enough to be able to be tracked. In addition, the radioactive tags have short enough half lives such that they are not present for long enough in the body to cause harm.
Here is a video explaining the usefulness of radioactive isotopes for imaging cancerous growths in the body.
For example, regular nitrogen can be replaced by a radioactive isotope of nitrogen in a sample, such as DNA, and then this sample can be left to replicate in an environment lacking these radioactive tags. The DNA is then radioactively tagged because it's nitrogenous bases have been replaced with radioactive isotopes. Subsequent generations of DNA replication can be evaluated based on their radioactivity; the more radioactive a generation, the more of the original DNA sample is present in it. A similar method, using isotropic tagging based on different molecular weights instead of radioactivity, was used to determine that DNA replication was semi-conservative. The method of radioactive tagging can be used to track the movement and distribution of molecules throughout biological reactions and processes.
Another application of radioactive tagging is following a biological process happening in vivo, such as cellular respiration. If a glucose molecule is radioactively tagged using radioactive carbon, the molecule can be tracked throughout the process of glycolysis and it's breakdown into pyruvate, and tracked through the rest of the cycle until it is expelled as carbon dioxide. This method of tracking is very simple, needing only a radioactive isotope to introduce into the biological system, and a device to track the movement of the radioactive molecule throughout the body.
Usage of this method in live humans and other animals is relatively safe because the radioactive tags are used in small enough quantities to not cause harm to the organism, but large enough to be able to be tracked. In addition, the radioactive tags have short enough half lives such that they are not present for long enough in the body to cause harm.
Here is a video explaining the usefulness of radioactive isotopes for imaging cancerous growths in the body.
In the video, radioactive atoms are attached to glucose carrier molecules in order to tag them. These glucose molecules, and their radioactive tags, are absorbed very quickly by cancerous cells because they need the energy from the glucose in order to fuel their rapid growth. When these molecules are absorbed, their radioactive components react with the environment of the cell, emitting photons that can be captured by the PET scanner. As a result, an image of the distribution of radioactive tracers, which are abundant in the cancerous cell, can be formed.
Radioactive tagging was used by Hershey and Chase in their experiments in order to determine that DNA is the genetic information of life forms. More information on their research is located on their page.
Radioactive tagging was used by Hershey and Chase in their experiments in order to determine that DNA is the genetic information of life forms. More information on their research is located on their page.