DNA sequences. A magnifying glass over two DNA sequences. The sequences also known as an autoradiogram is four rows of irregularly spaced black bands. A DNA sample can be taken from body tissue such as hair, blood and saliva. The DNA is then fragmented with enzymes and arrayed by size by electrophoresis. The banding pattern is then exposed onto an X-ray film. The bands represent the positioning of the base pairs (cytosine- guanine and adenine-thymine) on the DNA chain. This makes up the genetic code which is unique to every person. It can be used in hereditary tests such as paternity suits and in criminal identification.