Practice question

Tandem repetitive DNA is classified by repeat unit length and array size. Microsatellites, SSR or STR, contain 1-6 bp motifs, minisatellites or VNTR contain 10-100 bp motifs, while macrosatellites exceed 100 bp and can span kilobases, forming large heterochromatic blocks at centromeres, telomeres and heterochromatic regions. The greater than 100 base pair definition distinguishes macrosatellite organization, which often shows higher-order repeat structure, epigenetic silencing and copy number variation. Such large repeats are unsuitable for standard PCR microsatellite assays but crucial for chromosome structure and large-scale genomic variation studies.