End labeling is performed using polynucleotide kinase. Autoradiography involves the exposure of photographic film by a radioactive source. Geiger counters monitors the ionization of gases when radioactive particles interact with them. Scintillation counting measures the light emission of molecules that fluoresce upon interaction with radioactive material. This last method allows for accurate quantitation of radioactivity.
Ethidium bromide is used to detect the nucleic acids.
The pore size of the matrix depends on the concentration of gel materials and the degree of crosslinking. The resolution of acrylamide gels is excellent - DNA fragments that differ in size by just one nucleotide an be separated. Agarose gels are ususally used to resolve larger fragments. Detection of nucleic acids in gels is typically accomplished with UV or autoradiography. These nucleotide derivatives do not have 3' hydroxyl groups, having instead a 3' hydrogen.