Mitochondria, the powerhouses of our cells, would have been good models for the “Got Milk?” campaign; they have an insatiable thirst for calcium. 

“It’s an incredibly strong phenomenon. When you give mitochondria a pulse of calcium, they just take in all of it,” said Vamsi Mootha, professor of systems biology at Harvard Medical School and professor of medicine at Massachusetts General Hospital.

Taking in and sending out calcium appears to be one way mitochondria coordinate their activity with the rest of the cell. Cells may send calcium signals to mitochondria to turbocharge energy production during exercise. Absorbing and selectively releasing calcium may also allow mitochondria to fine-tune cellular signals that influence the release of neurotransmitters, muscle contraction, insulin release, gene activity and cell growth...