Cellular Respiration
Definition and meaning of Cellular Respiration in chemistry.
Cellular Respiration is a set of metabolic reactions occurring in cells to convert biochemical energy from nutrients into adenosine triphosphate and release waste products. The most efficient form is aerobic respiration, which uses oxygen to fully oxidize glucose into carbon dioxide and water.
In more detail
The process unfolds in three primary stages known as glycolysis, the citric acid cycle, and oxidative phosphorylation. Glycolysis takes place in the cytoplasm, breaking down one molecule of glucose into two molecules of pyruvate and yielding a small net gain of ATP. In the presence of oxygen, pyruvate enters the mitochondria, where it is fully oxidized in the citric acid cycle, releasing carbon dioxide and transferring high-energy electrons to carriers like NADH and FADH2. These electron carriers donate electrons to the electron transport chain, driving the pumping of protons across the inner mitochondrial membrane. The resulting proton gradient powers ATP synthase to produce a large amount of ATP through chemiosmosis, with oxygen acting as the final electron acceptor to form water.
Key facts
| Field | Biochemistry |
|---|---|
| Formula | C6H12O6 |
| Molar mass | 180.16 g/mol |
| Maximum ATP yield | 30 to 32 ATP per glucose |
| Primary location | Mitochondria |
| Final electron acceptor | Oxygen |
During a marathon, human muscle cells continuously undergo aerobic cellular respiration to generate the massive amounts of ATP required for sustained muscle contraction.
Frequently asked questions
What happens when cells do not have enough oxygen for respiration?
Without adequate oxygen, cells must rely on anaerobic respiration or fermentation, which yields significantly less ATP and produces byproducts like lactic acid or ethanol.
Is cellular respiration the reverse of photosynthesis?
While the overall chemical equations are inverses of each other, the biochemical pathways, enzymes, and cellular locations are entirely different.