IB Biology: Respiration Respiration Define cell respiration. Cell respiration is the carefully regulated release of energy from organic compounds in cells in the form of ATP (Adenosine Triphosphate).. This process is controlled by proteins known as enzymes. State that, in cell respiration glucose in the cytoplasm is broken down by glycolysis into pyruvate, with a small yield of ATP. The process of respiration always begin in the cytoplasm, where reactions occur converting glucose into 2 pyruvates (3-carbon compounds). This conversion does not require oxygen and produces a very small amount of ATP. In the cytoplasm: Glucose –> 2 Pyruvate Explain that, during anaerobic cell respiration, pyruvate can be converted in the cytoplasm into lactate, or ethanol and carbon dioxide, with no further yield of ATP. In the absence of oxygen, the pyruvate stays in the cytoplasm and does not move into the mitochondria. For humans: Pyruvate –> Lactic Acid For yeast: Pyruvate –> Ethanol + Carbon Dioxide Explain that, during aerobic cell respiration, pyruvate can be broken down in the mitochondrion into carbon dioxide and water with a large yield of ATP. If oxygen is present, the pyruvate will move into a mitochondrion where it is broken down to release Carbon Dioxide, Water, and a high yield of ATP.