There has been an enormous amount of progress made since Watson and Crick first discovered the double helix structure of DNA in 1958. The original and deceptively simple version held that genes encoded proteins in our cells. These proteins, in turn, did the work necessary to keep an organism alive. At that time it was thought that only 1.5% of the genome was actually used for this purpose. The other 98.5% of the genome was dubbed “junk DNA” assumed to have been left over from a millennia of mutations during life’s millions of years of evolution on this planet.
What is amazing , to me at least, is the fact that, as complicated as we humans are, we only have about 2,000 more genes, or about 10% more, than the microscopic roundworm. And the roundworm doesn’t even have a brain! What we do have in abundance are RNA transcripts which are produced by these genes of ours. It turns out these RNA transcripts do the real work of differentiating us from roundworms.
A good analogy would be to picture the building of a garage versus the building of a hospital. The basic materials like dimension lumber, sheet rock, plumbing pipes, wiring and roofing are the same. The tools necessary to assemble these materials, like hammers and nails, saws and screws are the same also. What is different is the complexity of the structure, or the blueprints. The construction of a hospital involves the orchestration of hundreds or even thousands of rules which specify which materials are used, where they are used, and when. In our cells the RNA transcripts provide the assembly instructions for our body’s blueprints, and when they spring into action.
Although it took less than a decade to sequence our DNA once the tools were available, it will probably take decades longer to unravel the regulatory function of our RNA transcripts. The complex interweaving of genes, transcripts, and the regulation each provides has spawned an alphabet soup of anacronyms describing these newly found genetic roles.
One thing is certain. As we begin to unravel the mystery that is our genetic heritage, our picture is going to get a great deal cloudier and more complicated before it begins to get sorted out again.