The organelle considered the "powerhouse" of the cell is the mitochondrion.

Here's why:

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

* Cellular respiration: Mitochondria use glucose and oxygen to create ATP through a series of chemical reactions.

* Energy conversion: They are essentially energy converters, transforming chemical energy from food into usable energy for the cell.

While other organelles contribute to cellular processes, the mitochondrion's role in ATP production makes it the key energy source for the cell.