Chromosome. Computer artwork of a chromosome and a DNA autoradiogram. Chromosomes contain the genetic material DNA (deoxyribonucleic acid). They can form these two identical copies (chromatids), aligned parallel to each other and joined at an area called a centromere. The banding (dots) on the arms of the chromatids are formed by staining the chromosome. Each of the 46 human chromosomes can be identified by a unique banding pattern. DNA carries the genetic code, unique for every individual, that controls the development and functioning of every living organism. The code is formed by the sequence of nucleotide bases in DNA, obtained as the bands (blue) on the autoradiogram.