DNA sequences & chromosomes. Computer artwork of an autoradiogram of DNA (deoxyribonucleic acid) sequences. A close up view of a sequence is superimposed in the foreground. Also in the foreground are chromosomes (mauve). In the cells of an organism, DNA is found in chromosomes. Here the DNA sequences are four rows of irregularly spaced black bands. A DNA sample can be taken from body fluids such as blood, and body tissues. The DNA is then fragmented with enzymes to form the banding pattern. The bands represent the positioning of the base pairs on the DNA molecule. This makes up the genetic code in the form of genes which is unique to every person.