Medical Genetics Simple Sequence DNA All eukaryotes have more than one ype of simple sequence DNA. The repeat unit length is usually 5-10 bp but may be as short as 2 or as long as 200.These repeat units are arranged in head to tail tandem arrays which vary in length. The longest tandem array known so far is that of human alphoid dna which has a total array length of approximately 5 million base pairs but certain simple sequences have an array length of only a few hundred base pairsMedical Genetics Simple Sequence DNA All eukaryotes have more than one type of simple sequence DNA. The repeat unit length is usually 5-10 bp but may be as short as 2 or as long as 200. These repeat units are arranged in head to tail tandem arrays which vary in length. The longest tandem array known so far is that of human alphoid DNA which has a total array length of approximately 5 million base pairs but certain simple sequences have an array length of only a few hundred base pairs