The cell organelle that breaks down food molecules and releases energy is the mitochondrion.

Here's why:

* Cellular Respiration: Mitochondria are the powerhouses of the cell. They are the sites of cellular respiration, where glucose (a sugar) is broken down in a series of chemical reactions.

* Energy Production: This process releases energy stored in the chemical bonds of glucose, primarily in the form of ATP (adenosine triphosphate), the cell's primary energy currency.

Let me know if you'd like more information about cellular respiration or the structure of mitochondria!