Organization of repetitive DNA elements between genes
Protein-coding genes comprise both expressed exons (dark green) and
intervening introns (light
grey regions). Repetitive
DNA elements may be interspersed both within and between genes. The
latter include short or long interspersed elements (SINEs and LINEs), and VNTRs ( micro- & minisatellites),
which comprise highly variable
numbers of tandem repeat sequences.
Other repetitive elements found between coding genes include centromeric heterochromatin, which are genetically inert regions near the chromosomal centromeres that serve as an attachment point for microspindles, and nucleolus-organizing regions (NORs), which comprise tandem repeats of rDNA genes on particular chromosomes. Centromeres and NORs are frequently detectable cytologically.
Other repetitive elements found between coding genes include centromeric heterochromatin, which are genetically inert regions near the chromosomal centromeres that serve as an attachment point for microspindles, and nucleolus-organizing regions (NORs), which comprise tandem repeats of rDNA genes on particular chromosomes. Centromeres and NORs are frequently detectable cytologically.