Here's why:

* Energy production: Mitochondria are responsible for the production of ATP (adenosine triphosphate), the primary energy currency of cells. This process is known as cellular respiration.

* Metabolic processes: Mitochondria also play a role in other metabolic processes like fatty acid oxidation and amino acid metabolism.

So, while other organelles have important roles, the mitochondrion is the powerhouse that keeps the cell running.