Cellular respiration requires several key components and conditions to occur, primarily to produce ATP by breaking down glucose:
- Glucose : This is the main fuel molecule, a carbohydrate that cells break down to release energy. Glucose is split into two molecules of pyruvate during glycolysis in the cytoplasm
- Oxygen : Cellular respiration is mostly an aerobic process, meaning it requires oxygen. Oxygen acts as the final electron acceptor in the electron transport chain, allowing for efficient ATP production. Without oxygen, cells resort to less efficient anaerobic respiration or fermentation
- Mitochondria : In eukaryotic cells, mitochondria are essential for the later stages of cellular respiration (the citric acid cycle and oxidative phosphorylation). Pyruvate produced in glycolysis is transported into mitochondria for further oxidation
- Enzymes and electron carriers : Various enzymes catalyze the steps of glycolysis, the citric acid cycle, and the electron transport chain. Electron carriers such as NAD+ and FAD are reduced to NADH and FADH2, which transfer electrons to the electron transport chain to generate a proton gradient used for ATP synthesis
In summary, the main reactants needed for cellular respiration to occur are glucose and oxygen. The process involves glycolysis in the cytoplasm, followed by pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation in the mitochondria. The products are carbon dioxide, water, and ATP, with ATP serving as the usable energy currency for the cell
