Professors P. Motta & T. Naguro/Photo Researchers
Each of our cells hangs in a delicate balance between life and death. Which path the cell takes depends on a dense web of signaling pathways that all converge on a single cellular switch, the mitochondrion. Most of the time, pro-life signals keep the mitochondrial membrane intact and encourage the organelle to churn out ATP. But when signals from the outside or accumulated toxins within the cell tip the scales, mitochondria push the cell down a carefully orchestrated pathway to death. To paraphrase the old saw, mitochondria are 99% respiration, 1% expiration.
This death march, dubbed apoptosis in the 1970s, plays roles in both development and disease. It sculpts our hands and feet, destroys cells that contain damaged DNA, and helps maintain the appropriate number of cells throughout our lives. It also has been implicated in cancer, neurodegenerative disorders, and infection, as well ...
