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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. [ 16 ]
[1] [2] In this type of respiration, oxygen serves as the terminal electron acceptor for the electron transport chain. [1] Aerobic respiration has the advantage of yielding more energy (adenosine triphosphate or ATP) than fermentation or anaerobic respiration, [3] but obligate aerobes are subject to high levels of oxidative stress. [2]
NADH and FADH 2 undergo oxidation in the electron transport chain by transferring an electrons to regenerate NAD + and FAD. Protons are pulled into the intermembrane space by the energy of the electrons going through the electron transport chain. Four electrons are finally accepted by oxygen in the matrix to complete the electron transport chain.
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 ...
During normal aerobic respiration the ratio would be somewhere between these values, as the TCA cycle produces both NADH and ubiquinol. The resulting P/O ratio would be the ratio of H/O and H/P; which is 10/3.67 or 2.73 for NADH-linked respiration, and 6/3.67 or 1.64 for UQH2-linked respiration, with actual values being somewhere between.
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.
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 ...