[In Depth] Why do cells' power plants hang on to their own genomes?
A new study suggests why mitochondria—the powerhouses of the cell—still hang on to tiny genomes of their own. These organelles originated more than a billion years ago as single-celled organisms that were swallowed by larger cells. Since then the mitochondrial genome has shrunk, with many genes migrating to the cell nucleus. But that makes it all the more puzzling that mitochondria have retained any genes at all, especially considering that mutations in some of those genes can cause rare but crippling diseases. The new study, based on an analysis of more than 2000 different mitochondrial genomes, revealed some common features in the genes that mitochondria have retained. Many, for example, code for proteins central to these the organelles' energy-generating complexes. Author: Laurel Hamers