Exon / Intron
structure
of some vertebrate genes
In eukaryotes, the intervening
introns
separate the expressed exon
regions. Intron / Exon organization varies widely among
genes: a single
intron may constitute a minority of the locus, as in insulin,
or
multiple introns may make up a majority of the sequence, as in ovalbumin.
[The ovalbumin gene was the first gene in which the intron / exon
structure was discovered].
Some genes are millions of bp in length, and contain
dozens of introns that constitute >99% of the
sequence.