Organization of the Human genome
A 'typical'
50kbp region of the human genome is shown, with putative
gene regions expanded above. Exons
constitute only a few percent of the region. Introns make up the bulk
of gene regions, and along with intergenic regions
are interuppted by repeat
sequences (cf. locus FLJ10143).
Many of the these dispersed repeats are members of the Alu
family, a 200~300 bp repeat dispersed many
hundreds of thousands of times across the genome.
Although
repetitive DNA is sometimes referred to as "junk
DNA", this probably represents current
states of unknowledge. For example, it appears likely
that repetitive elements assist in alternative
splicing of exons to produce different transcripts
with different properties from the same coding
region, which might explain how humans are able to
function with so few genes..
Figure © 2012 TA Brown, Introduction to Genetics (1st ed.); additional text © 2012 by Steven M. Carr