Answer:
The most basic answer to this is that the mitochondria generates energy for the cell's power needs.
But... (elaborated in explanation.)
Step-by-step explanation:
As you may know, the mitochondria is the powerhouse of cells.
The mitochondria can ALSO identify cell death, and determine which cells (dead) must be destroyed.
The mitochondria helps regulate calcium storage, but quickly absorbing calcium ions until needed.
And lastly, the mitochondria can also help generate heat. A process called proton leak. This is known as non-shivering thermogenesis.