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An electron transport chain (ETC [1]) is a series of protein complexes and other molecules which transfer electrons from electron donors to electron acceptors via redox reactions (both reduction and oxidation occurring simultaneously) and couples this electron transfer with the transfer of protons (H + ions) across a membrane.
Anaerobic respiration is used by microorganisms, either bacteria or archaea, in which neither oxygen (aerobic respiration) nor pyruvate derivatives (fermentation) is the final electron acceptor. Rather, an inorganic acceptor such as sulfate ( SO 2− 4 ), nitrate ( NO − 3 ), or sulfur (S) is used. [ 21 ]
The chain of redox reactions driving the flow of electrons through the electron transport chain, from electron donors such as NADH to electron acceptors such as oxygen and hydrogen (protons), is an exergonic process – it releases energy, whereas the synthesis of ATP is an endergonic process, which requires an input of energy.
Within aerobic respiration, the P/O ratio continues to be debated; however, current figures place it at 2.5 ATP per 1/2(O 2) reduced to water, though some claim the ratio is 3. [5] This figure arises from accepting that 10 H + are transported out of the matrix per 2 e − , and 4 H + are required to move inward to synthesize a molecule of ATP.
In aerobic respiration, oxygen serves as the recipient of electrons from the electron transport chain. Aerobic respiration is thus very efficient because oxygen is a strong oxidant. Aerobic respiration proceeds in a series of steps, which also increases efficiency - since glucose is broken down gradually and ATP is produced as needed, less ...
The last process in aerobic respiration is oxidative phosphorylation, also known as the electron transport chain. Here NADH and FADH 2 deliver their electrons to oxygen and protons at the inner membranes of the mitochondrion, facilitating the production of ATP. Oxidative phosphorylation contributes the majority of the ATP produced, compared to ...
There are three energy-transducing enzymes in the electron transport chain - NADH:ubiquinone oxidoreductase (complex I), Coenzyme Q – cytochrome c reductase (complex III), and cytochrome c oxidase (complex IV). [1] Complex I is the largest and most complicated enzyme of the electron transport chain. [2] The reaction catalyzed by complex I is:
Oxidative phosphorylation produces 26 of the 30 equivalents of ATP generated in cellular respiration by transferring electrons from NADH or FADH2 to O 2 through electron carriers. [10] The energy released when electrons are passed from higher-energy NADH or FADH2 to the lower-energy O 2 is required to phosphorylate ADP and once again generate ...