**Overview of Cellular Respiration**
– Cellular respiration is the process of converting nutrients into energy in the form of ATP.
– It involves aerobic respiration that requires oxygen to produce ATP.
– Carbohydrates, fats, and proteins are consumed as reactants in this process.
– Pyruvate is fully oxidized in the mitochondria through the citric acid cycle to generate energy.
– Most ATP is produced through oxidative phosphorylation in this metabolic pathway.
**Specific Steps in Cellular Respiration**
– Glycolysis is a metabolic pathway in the cytosol converting glucose into pyruvate and generating ATP.
– Oxidative decarboxylation of pyruvate occurs in the mitochondria or cytosol to form acetyl-CoA and CO2.
– The citric acid cycle, also known as the Krebs cycle, produces acetyl-CoA from pyruvate for further respiration.
**Efficiency and Comparison of Metabolic Pathways**
– Aerobic metabolism is significantly more efficient than anaerobic metabolism, yielding up to 15 times more ATP.
– Post-glycolytic reactions occur in the mitochondria of eukaryotic cells.
– Plant respiration contributes to approximately half of the CO2 generated annually by terrestrial ecosystems.
**Oxidative Phosphorylation**
– This process occurs in the mitochondrial cristae in eukaryotes, involving the electron transport chain and ATP synthase.
– It establishes a proton gradient for ATP synthesis and results in the formation of water by transferring electrons to oxygen.
**Other Aspects of Cellular Respiration**
– Fermentation is an anaerobic process where pyruvate is converted to waste products like lactic acid or ethanol.
– Anaerobic respiration is utilized by microorganisms with inorganic electron acceptors, allowing ATP production without oxygen.
– Various tools and indicators like respirometry and tetrazolium chloride are used to study cellular respiration.
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Cellular respiration is the process by which biological fuels are oxidized in the presence of an inorganic electron acceptor, such as oxygen, to drive the bulk production of adenosine triphosphate (ATP), which contains energy. Cellular respiration may be described as a set of metabolic reactions and processes that take place in the cells of organisms to convert chemical energy from nutrients into ATP, and then release waste products.
Cellular respiration is a vital process that occurs in the cells of all living organisms.[better source needed] Respiration can be either aerobic, requiring oxygen, or anaerobic; some organisms can switch between aerobic and anaerobic respiration.[better source needed]
The reactions involved in respiration are catabolic reactions, which break large molecules into smaller ones, producing large amounts of energy (ATP). Respiration is one of the key ways a cell releases chemical energy to fuel cellular activity. The overall reaction occurs in a series of biochemical steps, some of which are redox reactions. Although cellular respiration is technically a combustion reaction, it is an unusual one because of the slow, controlled release of energy from the series of reactions.
Nutrients that are commonly used by animal and plant cells in respiration include sugar, amino acids and fatty acids, and the most common oxidizing agent is molecular oxygen (O2). The chemical energy stored in ATP (the bond of its third phosphate group to the rest of the molecule can be broken allowing more stable products to form, thereby releasing energy for use by the cell) can then be used to drive processes requiring energy, including biosynthesis, locomotion or transportation of molecules across cell membranes.