M. luteus can be found in many places such as the human skin, water, dust, and soil. Micrococcus is generally thought of as harmless bacterium, but there have been rare cases of Micrococcus infections in people with compromised immune systems, as occurs with HIV patients.
Therefore when used in gel electrophoresis, markers effectively provide a logarithmic scale by which to estimate the size of the other fragments (providing the fragment sizes of the marker are known). Protein, DNA, and RNA markers with pre-determined fragment sizes and concentrations are commercially available.
An electrophoresis gel, which can be used to determine a molecule's size. Treatment of the DNA sample with multiple restriction enzymes in various combinations enables the researcher to generate a restriction map of the original DNA fragment, which identifies the sites at the DNA where the restriction enzymes are.