satellite dna
The majority of the human genome is non-coding sequence. These sequences include regulatory sequences, and DNA with unknown functions. These sequences include tandem repeat elements known as satellite DNA , and transposons. Satellite DNA consists of very large arrays of tandemly repeating, non-coding DNA. The repeating units can be just a single base a mono nucleotide repeat , two bases a dinucleotide repeat , three bases a trinucleotide repeat or a much larger repeating unit. Some repeating units are several thousand base pairs long, and the total size of a satellite DNA segment can be several megabases without interruption.