Distribution of repetitive DNA elements within Exon / Intron structures
The 14 exons [numbered
dark-green units]
for a single protein-coding gene constitute a very small
portion of the total 50 Kbp region. The introns
[light-green areas]
include a number of families of repetitive DNA sequences, shown separately in
the exploded views below. These include short interspersed repeats
(SINES, including Alu
family sequences), long interspersed repeats
(LINEs, including the L1
family), long tandem repeats
(LTRs), and simple sequence repeats (SSRs),
also known as VNTRs
(Variable Number of Tandem Repeats)
or micro- or minisatellites.
Note that the SSRs occur as two- or four-base
motifs that are repeated n times each.