The answer is the mitochondria. The answer to this is the mitochondria. This is where all the protein and carbohydrates are kept in the cell. Carbohydrates are a main source of energy for all living things.
Mitochondria create ATP (Adenosine Triphosphate). ATP is the main energy source of the cell. When a cell needs energy, the cell breaks one phosphate off of the molecule, which then becomes Adenosine Diphosphate.
Cellular respiration's main goal is to produce ATP which is the energy currency of the cell. Most cellular functions require energy to work, and ATP is the source of that energy because of the stored up energy in its phosphates.