Where does the breakdown of Pyruvate using Oxygen take place?

Answer: The breakdown of pyruvate using oxygen takes place in the Mitochondria.

Mitochondria are found in most eukaryotic organisms and they are membrane-bound cell organelles. Its purpose is to generate energy. They produce most of the chemical energy required to power the cell's biochemical reactions. Adenosine Triphosphate (ATP) stores the chemical energy produced by the mitochondria. They have their own small chromosomes. Mitochondria is present in various body parts of humans in different amounts. The body parts that contain mitochondria are the muscle, liver, kidney, and brain.

Summary:

Where does the breakdown of Pyruvate using Oxygen take place?

Pyruvate breaks into carbon dioxide and water using oxygen in the Mitochondria. It is produced by glycolysis in the cytoplasm.