The process that breaks down food molecules to make ATP is called cellular respiration. It's a complex series of chemical reactions that occur in the cells of living organisms. Here's a simplified breakdown:

1. Glycolysis: This is the first step and occurs in the cytoplasm. Glucose (a sugar) is broken down into pyruvate, generating a small amount of ATP.

2. Citric Acid Cycle (Krebs Cycle): This occurs in the mitochondria and uses pyruvate to produce some ATP, but mainly generates electron carriers (NADH and FADH2).

3. Electron Transport Chain: This also occurs in the mitochondria and uses the electron carriers from the Krebs cycle to generate a significant amount of ATP. This is the main source of ATP during cellular respiration.

In summary:

* Food molecules (like glucose) provide the energy source.

* Cellular respiration breaks down these molecules in a series of steps.

* The energy released is used to create ATP, the primary energy currency of cells.

It's important to note that cellular respiration is not a single process, but rather a series of interconnected reactions. Each step is crucial for the overall production of ATP.