[pjschlic]

If I recall correctly from my bioinformatcs classes (years ago) - the non-coding DNA still serve many functions - a protective role by containing sequences which stabilize the structure of the DNA, or providing binding sites used in promoting or suppress gene expression. The non-coding are recognizable by different characteristics from the coding sections. Not to mention the fact that by definition, at least half the sequences are just the complement of a coding sequence - so putting in stop codons before and after on the complement would be useful to make sure it's not expressed. Add in structural sequences to create preferences of where it's safe to swap genes with the sister chromosome DNA during meiosis, and all sorts of other things, and you end up with quite a but of non-coding DNA still serving a purpose.