DNA fragments visualized by gel electrophoresis on agarose gel. DNA fragments corresponding to the ...

DNA fragments visualized by gel electrophoresis on agarose gel. DNA fragments corresponding to the region amplified by PCR are separated by electrophoresis according to size. They are then stained with ethidium bromide and can be visualized under ultraviolet light. The size of the DNA fragment can then be estimated by comparing its migration pattern to fragments of DNA of known size. Because the sequence of the DNA fragment is known, its molecular size can be determined; if the size of a particular DNA fragment amplified by PCR corresponds to the size of the fragment estimated by sequencing, that DNA fragment is confirmed to be the one amplified by the PCR primers.