Aerobic respiration occurs in the presence of oxygen and involves the complete breakdown of pyruvate into carbon dioxide and water in the mitochondria. Anaerobic respiration, such as fermentation, occurs in the absence of oxygen and may lead to the conversion of pyruvate into ethanol and carbon dioxide.
Describe the two main pathways of cellular respiration and their dependence on oxygen.
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The two main pathways of cellular respiration are aerobic and anaerobic respiration, both involving the breakdown of glucose for energy. Aerobic respiration occurs in the presence of oxygen and includes glycolysis, the Krebs cycle, and oxidative phosphorylation. These stages take place in the cytoplasm and mitochondria, yielding a substantial amount of ATP. In contrast, anaerobic respiration, like fermentation, occurs in the absence of oxygen, only involving glycolysis. While glycolysis still produces ATP, the overall yield is lower compared to aerobic respiration. Oxygen is essential for the complete extraction of energy through the Krebs cycle and oxidative phosphorylation in aerobic respiration.