Non-coding DNA before a protein coding sequence has a very important function obvious to any programmer: It is a large section of pattern-matching "if"s. Depen

Non-coding DNA before a protein coding sequence has a very important function obvious to any programmer: It is a large section of pattern-matching "if"s. Depending on the current state of the cell, various proteins will bind to the DNA in these places to either increase or restrict production of this specific protein. This allows multi-stage configuration of cellular protein production. If this won't be the case, the cell will produce an equal amount of all coded proteins, which would be silly. Source: something I learned while helping with coding for a paper in biology.