What are the main steps in aerobic respiration? Where does it take place?
Aerobic respiration involves complete oxidation of respiratory substrate in presence of oxygen. This entire process takes place in three steps: Glycolysis: This is the first step of aerobic respiration in which the respiratory substrate i.e. Glucose is broken down into pyruvate. It is divided into two phases : preparatory phase and pay-off phase. Glycolysis yields 2 molecules of NADH and 2 molecule of ATP per molecule of glucose. Link reaction: The pyruvate produced at the end of glycolysis cannot enter the mitochondrial matrix. It undergoes oxidative decarboxylation to produce acetyl CoA and NADH. Kreb’s cycle: The acetyl CoA can enter the mitochondrial matrix, where it combines with oxaloacetate to form citrate and marks the beginning of a cycle of reaction called Kreb’s cycle . During Kreb’s cycle , carbon dioxide , NADH and FADH are released at different steps. Oxidative phosphorylation: This is the final step of aerobic respiration in which NADH and FADH are oxidized and NAD+ and FAD+ is restored back. The electrons are transferred to the molecular oxygen producing water. The electron transport system facilitates this transfer of electrons. Aerobic respiration takes place in almost all eukaryotes. Three steps of it occurs at different sites. Glycolysis takes place in cytoplasm, Kreb’s cycle takes place in mitochondrial mtrix and Oxidative phosphorylation in mitochondrial membrane.
