Remember junk (non-coding) DNA?
From Pacific Standard:
Genes don’t consistently do what we once thought they would, so it’s time to reconsider what we mean when we say the word.
Our concept of a gene is also challenged by the fact that much of the function in our DNA is located outside of conventionally defined genes. These “non-coding” functional DNA segments regulate when and where conventional protein-coding genes operate. For our biology, non-coding regulatory DNA elements are as consequential as genes, but their properties are even more difficult to define because their function isn’t based on the well-understood Genetic Code and their boundaries are even fuzzier than gene boundaries. As a result, non-coding regulatory DNA elements are much more difficult to count. One consortium of researchers put the number of regulatory DNA segments in the human genome between 580,000 and 2.9 million, while just last month a different consortium claimed that there are only 43,000. Regardless of how you count them, it’s clear that these non-gene regulatory DNA elements far outnumber conventional genes. It is hard not to wonder, then, what good is the concept of a gene if it doesn’t include most of our functional DNA?
In the aftermath of the Human Genome Project, biologists are struggling with the definition of a gene, but why should this matter to anyone else? It matters because the molecular concept of the gene that has dominated biomedical research for the last half-century is increasingly ill-suited for our efforts to understand the role of genetics in human biology. Giving a physical meaning to the concept of a gene was a triumph of 20th-century biology, but as it turns out, this scientific success hasn’t solved the problems we hoped it would.
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