In 2003, when the human genome had been sequenced, many people expected a welter of new therapies to follow, as biologists identified the genes associated with particular diseases.
But the process that translates genes into proteins turned out to be much more involved than anticipated. Other elements — proteins, snippets of RNA, regions of the genome that act as binding sites, and chemical groups that attach to DNA — also regulate protein production, complicating the relationship between an organism’s genetic blueprint, or genotype, and its physical characteristics, or phenotype.
In the latest issue of the Proceedings of the National Academy of Sciences, researchers from MIT and the Whitehead Institute for Biomedical Research argue that biologists trying to explain the connection between genotype and phenotype need to consider yet another factor: genetic material that doesn’t come from an organism’s chromosomes at all.
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Through a combination of clever lab experiments and quantitative analysis, the researchers showed that the consequences of deleting genes in yeast cells can’t be explained without the additional consideration of nonchromosomal genetic material — in particular, from the intracellular bodies known as mitochondria and from viruses that can linger in dividing cells.
Read the full, original story: It’s in the genes — but whose?
