External transcribed spacer
From Wikipedia, the free encyclopedia
External transcribed spacer (ETS) refers to a piece of non-functional RNA, closely related to the internal transcribed spacer, which is situated outside structural ribosomal RNAs (rRNA) on a common precursor transcript.[1] ETS sequences characteristic to an organism can be used to trace its phylogeny.[2]
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/a/ac/Eucaryot_rdna.png/640px-Eucaryot_rdna.png)