Ans.
Glucose catabolism is defined as the breakdown of glucose molecule to provide energy to the cells, in the form of ATP (adenosine triphosphate) molecules. In first step of glucose calabolism, glucose is converted into pyruvate. In the absence of oxygen, pyruvate converts into either lactic acid (lactic acid fermentation) or ethanol (alcoholic fermentation).
In the presence of oxygen, pyruvate enters into Krebs cycle, in the form of acetyl-coA. NADH, FADH2, and CO2 molecules are released by Krebs cycle. The NADH and FADH2 molecules enter into electron transport chain that occurs in inner mitochondrial membrane and results in formation of energy-giving ATP molecules.
In given diagram, a). represents pyruvate molecule, b). represents anaerobic respiration, c). represents NADH or FADH2 molecules, and d). represents ATP molecules.
