Protein-coding sequences account for only a very small fraction of the genome ( approximately 1.5 % ) , and the rest is associated with non-coding RNA molecules , regulatory DNA sequences , LINEs , SINEs , introns , and sequences for which as yet no function has been elucidated .
In fact , only about 1.5 % of the genome codes for proteins , while the rest consists of non-coding RNA genes , regulatory sequences , and introns .