Cell Respiration

2.7.1. Define cell respiration.

Cell respiration is the controlled release of energy in the form of ATP from organic compounds in cells.

2.7.2. State that in cell respiration, glucose in the cytoplasm is broken down into pyruvate with a small yield of ATP.
In cell respiration, glucose in the cytoplasm is broken down into pyruvate with a small yield of ATP.

2.7.3. Explain that in anaerobic cell respiration, pyruvate is converted into lactate or ethanol and carbon dioxide in the cytoplasm, with no further yield of ATP.
In anaerobic cell respiration, pyruvate is converted into either lactate by lactic acid fermentation or ethanol and carbon dioxide during alcohol fermentation. This produces no further yield of ATP. The ethanol and carbon dioxide are produced in yeast whereas lactate is produced in humans.

2.7.4. Explain that in aerobic cell respiration, pyruvate is broken down in the mitochondrion into carbon dioxide and water with a large yield of ATP.
In aerobic respiration, each pyruvate enters the Krebs cycle, a series of chemical reactions within the mitochondria. Just before this cycle, the pyruvate is decarboxylated, which produces the carbon dioxide, and the remaining two-carbon molecule reacts with a reduced Coenzyme A, and at the same time one NADH+H+ is formed. The pyruvate then enters the cycle, with the end result being the production of 3 NADH, 3 H+, 3 carbon dioxide molecules,and one ATP. The NADH and H+ molecules will be used in the electron transport chain (ETC), where the H+ will react with oxygen to produce water. The result of the ETC is a large yield of ATP.