An electron transport chain (ETC[1]) is a series of protein complexes and other molecules that 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. Many of the enzymes in the electron transport chain are embedded within the membrane.
The flow of electrons through the electron transport chain is an exergonic process. The energy from the redox reactions creates an electrochemical proton gradient that drives the synthesis of adenosine triphosphate (ATP). In aerobic respiration, the flow of electrons terminates with molecular oxygen as the final electron acceptor. In anaerobic respiration, other electron acceptors are used, such as sulfate.
In an electron transport chain, the redox reactions are driven by the difference in the Gibbs free energy of reactants and products. The free energy released when a higher-energy electron donor and acceptor convert to lower-energy products, while electrons are transferred from a lower to a higher redox potential, is used by the complexes in the electron transport chain to create an electrochemical gradient of ions. It is this electrochemical gradient that drives the synthesis of ATP via coupling with oxidative phosphorylation with ATP synthase.[2]
In eukaryotic organisms, the electron transport chain, and site of oxidative phosphorylation, is found on the inner mitochondrial membrane. The energy released by reactions of oxygen and reduced compounds such as cytochrome c and (indirectly) NADH and FADH2 is used by the electron transport chain to pump protons into the intermembrane space, generating the electrochemical gradient over the inner mitochondrial membrane. In photosynthetic eukaryotes, the electron transport chain is found on the thylakoid membrane. Here, light energy drives electron transport through a proton pump and the resulting proton gradient causes subsequent synthesis of ATP. In bacteria, the electron transport chain can vary between species but it always constitutes a set of redox reactions that are coupled to the synthesis of ATP through the generation of an electrochemical gradient and oxidative phosphorylation through ATP synthase.[3]
^Lyall, Fiona (2010). "Biochemistry". Basic Science in Obstetrics and Gynaecology. pp. 143–171. doi:10.1016/B978-0-443-10281-3.00013-0. ISBN 978-0-443-10281-3.
^Anraku Y (June 1988). "Bacterial electron transport chains". Annual Review of Biochemistry. 57 (1): 101–32. doi:10.1146/annurev.bi.57.070188.000533. PMID 3052268.
^Kracke F, Vassilev I, Krömer JO (2015). "Microbial electron transport and energy conservation - the foundation for optimizing bioelectrochemical systems". Frontiers in Microbiology. 6: 575. doi:10.3389/fmicb.2015.00575. PMC 4463002. PMID 26124754. – This source shows four ETCs (Geobacter, Shewanella, Moorella , Acetobacterium) in figures 1 and 2.
and 28 Related for: Electron transport chain information
An electrontransportchain (ETC) is a series of protein complexes and other molecules that transfer electrons from electron donors to electron acceptors...
electrontransportchain. In aerobic organisms undergoing respiration, electrons are shuttled to an electrontransportchain, and the final electron acceptor...
cell's outer membrane. These linked sets of proteins are called the electrontransportchain. In eukaryotes, five main protein complexes are involved, whereas...
single electrontransportchain). This means that combined with the Krebs Cycle and glycolysis, the efficiency for the electrontransportchain is about...
converted to more ATP through an electrontransportchain with oxygen and protons (hydrogen) as the "terminal electron acceptors". Most of the ATP produced...
also enable electron transfer as they form part of the electrontransportchain. Cytochrome a, cytochrome b, and cytochrome c have such electron transfer...
flavin adenine dinucleotide (FAD). The carriers pass electrons to the electrontransportchain (ETC) in the inner mitochondrial membrane, which in turn...
be photosynthetic). Instead of a chlorophyll-type receptor and electrontransportchain, proteins such as halorhodopsin capture light energy with the aid...
electrochemical gradient to carry out processes within cells such as in the electrontransportchain, an important function of cellular respiration that happens in...
chemiosmotic potential. The carriers in the electrontransportchain use some of the electron's energy to actively transport protons from the stroma to the lumen...
respiratory electrontransportchain in mitochondria. The heme group of cytochrome c accepts electrons from the bc1 Complex III and transports them to Complex...
synthesis of ATP. This electrochemical gradient is generated by the electrontransportchain and allows cells to store energy in ATP for later use. In prokaryotic...
FADH2, which are electron carriers used in the electrontransportchain. It is named as such because the beta carbon of the fatty acid chain undergoes oxidation...
reaction through electron transfer, and of providing energy to a proton pump and eventually ATP, for instance in cyclic electrontransport. When photosystem...
and prochlorophytes because of its role as primary electron donor in the electrontransportchain. Chlorophyll a also transfers resonance energy in the...
respiration, ATP synthase is coupled with an electrontransportchain in which oxygen acts as a terminal electron acceptor. In July 2020, marine biologists...
phosphorylation. The final step of cellular respiration is the electrontransportchain, composed of four complexes embedded in the inner mitochondrial...
fumarate by the enzyme succinate dehydrogenase in complex 2 of the electrontransportchain which is involved in making ATP, and as a signaling molecule reflecting...
respiratory chain, while the thylakoid membrane hosts an interlinked respiratory and photosynthetic electrontransportchain. Cyanobacteria use electrons from...
to drive electrons in a reverse direction through an electrontransportchain and is thus the reverse process as forward electrontransport. In some cases...
electron in an electrontransportchain, such as oxygen during cellular respiration, or the last cofactor to receive an electron within the electron transfer...
protons across a biological membrane, mediated by flow of electrons through an electrontransportchain. This stores energy in a proton gradient. As the protons...
the last enzyme in the respiratory electrontransportchain of cells located in the membrane. It receives an electron from each of four cytochrome c molecules...
is a terpenoid-quinone (meroterpenoid) molecule involved in the electrontransportchain in the light-dependent reactions of photosynthesis. The most common...
cyanobacteria by dissociating the reactions of ATP synthesis from the electrontransportchain. The result is that the cell or mitochondrion expends energy to...
Those that perform the electrontransportchain redox reactions ATP synthase, which generates ATP in the matrix Specific transport proteins that regulate...
and NADH. These reduced electron carriers can then be re-oxidized when they transfer electrons to the electrontransportchain. Ketosis is a metabolic...
Global Information