How do scientists look at DNA? As genetic analysis has become more precise, the average person may get the impression that modern geneticists have powerful microscopes in their labs that zoom in on the DNA molecule and reveal information. Fans of “Star Trek” television reruns will envision devices that are waved over tissue and produce meaningful DNA data. In reality, DNA analysis techniques reveal information by using a more indirect method of looking at the molecule. Electrophoresis is the central technique in this analysis.
Electrophoresis means to carry with electricity. The technique allows scientists to detect sequence variation among specific DNA segments based on how fast these segments are carried by electricity. There are two key facts that allow this technique to work.
1) Nucleotide sequence differences in one DNA segment compared to another can result in size differences in these segments.
2) Longer segments of DNA will be carried through the gel more slowly than shorter segments.
Speed comparisons bring to mind a race, so let’s think about electrophoresis using a racing analogy.