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Topic: Electron transfer chain


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In the News (Sat 28 Nov 09)

  
  Electron transfer chain - Wikipedia, the free encyclopedia
In eukaryotes, including humans, an ETC is found spanning the inner mitochondrial membrane (crista) and accepts electrons from electron donors such as NADH or succinate, shuttles these electrons from within the mitochondrial matrix across the inner mitochondrial membrane into the intermembrane space, where they ultimately reduce oxygen.
It is a soluble protein loosely associated with the inner mitochondrial membrane, and transfers electrons between Complexes III and IV.
Complex IV is the terminus of the electron transfer chain, where oxygen from the lungs is reduced by electrons and hydrogen protons (provided by NADH and/or FADH2) to make water.
en.wikipedia.org /wiki/Electron_transfer_chain   (301 words)

  
 Encyclopedia topic: Electron transfer chain   (Site not responding. Last check: 2007-11-07)
The electron transfer chain (also called the electron transport chain, ETC, e-train, or simply electron transport), is any series of protein complexes and lipid-soluable messengers that convert the reductive potential of energized electrons into a cross-membrane proton gradient.
They are used in photophosphorylation (additional info and facts about photophosphorylation) and respiration (The metabolic processes whereby certain organisms obtain energy from organic moelcules; processes that take place in the cells and tissues during which energy is released and carbon dioxide is produced and absorbed by the blood to be transported to the lu).
The electron transfer chain can be inhibited by various poison (Any substance that causes injury or illness or death of a living organism) s.
www.absoluteastronomy.com /encyclopedia/e/el/electron_transfer_chain.htm   (377 words)

  
 fespaper4
Feasibility of electron transfer from the ironsulfur protein in the distal conformation to cytochrome c1.
The central component of the electron transfer chain in mitochondria and in many aerobic or photosynthetic bacteria is a complex of membrane proteins known as the cytochrome bc1 complex, or ubiquinol:cytochrome c oxidoreductase (E.C. This enzyme complex catalyzes electron transfer from ubiquinol to a soluble cytochrome c, coupled to translocation of 2 H
Electron densities in the region of the globular extrinsic domain of this protein in our crystals are weaker than those in the rest of the structure, but clearly present and recognizable (Figure 5).
sb20.lbl.gov /cytbc1/cqbc1paper/short   (6442 words)

  
 [No title]   (Site not responding. Last check: 2007-11-07)
Model of electron flow is called the Z scheme Electron Transfer There are 4 distinct stages in electron transfer: Photosystem II splits water and transfers its electrons to plastiquinone.
Electrons from P680 eventually replaced by splitting of a molecule of water: 2H2O ---> O2 + 4 H+ + 4 e- Electrons are first held by Mn atom, then transferred to Z, then P680* H2O ----> Mn ---> Z ---> P680* Cytochrome b6f transfers e- from plastiquinone to plasticyanin.
Electrons are transferred from ferredoxin to NADP+ by NADP+ reductase Photons of light only involved in absorption of light in PS I and PS II --> provides energy to drive transfer of electrons to NADP+.
www2.una.edu /aoyen/CellBiology/LectureNotes/Chapter14notesSP05.doc   (1350 words)

  
 Agronomy 317 - Iowa State University
Photosynthesis is a series of reactions involving light absorption, energy conversion, electron transfer, and a multistep enzymatic pathway that converts CO and water into carbohydrates.
A pigment molecule becomes excited when absorption of light energy causes one of its electrons to shift from a lower-energy molecular orbit, which is closer to the pigments's atomic nuclei, to either of two more-distant, higher-energy orbitals.
Electrons become diverted from the transport chain, releasing excess energy into the cell and destroying cell membranes.
www.agron.iastate.edu /courses/Agron317/Photosynthesis_Inhibitors.htm   (2116 words)

  
 Electron Transfer Chain
of constituent electron carriers is represented in the diagram on p.
Electrons pass through a series of iron-sulfur centers in complex I, and are eventually transferred to coenzyme Q. Coenzyme Q accepts 2 e
The four electrons are transferred into the complex one at a time from cytochrome c.
www.rpi.edu /dept/bcbp/molbiochem/MBWeb/mb1/part2/redox.htm   (1331 words)

  
 Thiobacillus ferrooxidans
Their organisation into an electron transport chain bridging the span from Fe(II) to the membrane-bound, energy conserving electron transport pathways is still a matter of debate.
The electron transfer between the two b-hemes would be facilitated by their close midpoint potential values at acidic pH.
In subsequent cycles, hydroquinone would be reduced by one electron from the Rieske center and one electron from heme bL (the electron transfer between reduced heme bL and quinone being thermodynamically favorable).
bip.cnrs-mrs.fr /bip09/tb.html   (1527 words)

  
 [No title]   (Site not responding. Last check: 2007-11-07)
Abstract: Recent evidence from algal physiology and molecular biology confirms that photoinhibition is directly related to D1 protein damage and recovery, and D1 protein damage leads to a decrease in electron transfer or an increase in turnover time of the electron transfer chain.
In this study, the turnover time of the electron transfer chain is defined as a function of the relative concentration of D1 protein in reaction centre II and the photoinhibition processes due to D1 protein degradation are incorporated into a model of photosynthesis, initiated by Dubinsky et al.
Recent evidence from algal physiology and molecular biology confirms that photoinhibition is directly related to D1 protein damage and recovery, and D1 protein damage leads to a decrease in electron transfer or an increase in turnover time of the electron transfer chain.
www.entu.cas.cz /dtb/abstract/abstr7.html   (480 words)

  
 Chem 421 - Free Radical Polymerization - Chain Transfer
In many cases, a chain transfer agent is added deliberately to the reaction mixture.
Naturally, there are many even-electron species present in the reaction mixture (i.e., monomer, initiator, solvents, polymer chains, etc.), and all of therse may participate in transfer reactions, depending on the relative reactivities of the structures involved.
If the chain end radical attacks an atom on the backbone of the same or another chain, the result is a new radical that can reinitiate to form a branch.
www.chem.rochester.edu /~chem421/ct1.htm   (604 words)

  
 electron transfer chain - General Practice Notebook   (Site not responding. Last check: 2007-11-07)
The electron transfer chain is a series of enzyme and protein reactions within the inner mitochondrial membrane.
Combined with oxidative phosphorylation, it converts energy in the form of the electron transfer potential of NADH and FADH2 into the energy within the terminal phosphate bond of ATP.
FADH2 enters the chain at the level of coenzyme Q to yield 2 molecules of ATP.
www.gpnotebook.co.uk /cache/792002618.htm   (194 words)

  
 r2
The electron transfer path is able to tell us about changes that occur in a protein when it binds to another protein/subunit or substrate.
Direct electron transfer to the protein from the electrodes is not possible since the diiron center and tyrosyl radical are buried deep within the protein structure.
This mutation results in the mutant being inactive due to the electron transfer path being blocked and the electron not being able to move along its usual path, but still forms the normal amount of the catalytically essential tyrosyl radical.
www.chem.umn.edu /groups/stankovich/R2.html   (2407 words)

  
 Dianne K. Newman   (Site not responding. Last check: 2007-11-07)
Unlike most terminal electron acceptors that bacteria use for respiration (which are soluble and readily make their way to the cell to receive electrons from the membrane-bound molecules of the respiratory chain), ferric (hydr)oxide minerals are essentially insoluble under most environmental conditions.
Although my group has focused on electron shuttling in the context of mineral reduction, this is only one example in which extracellular electron transfer may be important.
We are using biochemical, genetic, and physiological approaches to determine where in the cell phenazines are reduced, how they interface with the membrane-bound electron transfer chain, what genes are activated in their presence, and whether cells that produce them gain energy (for growth or maintenance) from their production and/or recycling.
www.hhmi.org /research/investigators/newman.html   (1041 words)

  
 Photosynthesis
For oxidative phosphorylation the electrons come from hydrocarbon and carbohydrate structures, whereas in photosynthesis, the electrons have to be energized in the magnesium center of chlorophylls.
The electron, activated by a photon in the special pair at the lumenal side of the thylakoid membrane, is now located at the stromal side.
The electrons are transferred to photosystem I via plastocyanin and the protons are released into the thylakoid lumen of the chloroplast.
www.whatislife.com /reader2/Metabolism/pathway/photosyn.html   (1857 words)

  
 Plant respiratory NAD(P)H dehydrogenases
The NADH is oxidised and the electrons transferred to oxygen by the respiratory chain in the inner mitochondrial membrane (depicted in the image below).
The first step of the electron transfer chain in animal mitochondria, the oxidation of NADH, is carried out by the proton-pumping complex I. Plant mitochondria differ by having additional non-proton-pumping NAD(P)H dehydrogenases in the electron transfer chain.
Electron transfer through these enzymes will not be coupled to ATP synthesis and the efficiency of the respiratory process will be lower.
www.biol.lu.se /cellorgbiol/dehydrogenase/proj_descr.html   (440 words)

  
 [No title]   (Site not responding. Last check: 2007-11-07)
The heart of photosystem I is an electron transfer chain, a chain of chlorophyll (shown in green), phylloquinone (shown in orange) and three iron-sulfur clusters (yellow and red at the top).
At the top, the electron is transferred to a small ferredoxin protein (not shown here), which then ferries it on to the other steps of photosynthesis.
Because of the special design of their own cofactors, it is more difficult to add an electron to ferredoxin than it is to plastocyanin--normally, the flow would be in the opposite direction.
www.scripps.edu /mb/goodsell/pdb/pdb22/pdb22_2.html   (256 words)

  
 [No title]   (Site not responding. Last check: 2007-11-07)
Under conditions of full ambient sunlight, the rate of photosynthesis is determined by three main parameters: the availability of substrate, the flux of excitation to the photosystems, and the sensitivity of the electron transfer reactions to low lumenal pH.
We discuss the reactions of the electron transfer chain which might be effected by the proton gradient, and suggest that an important function of the diversion of excitation away from photochemistry is to prevent the lumenal pH from dropping into an inhibitory range.
In order to explore these processes we must be able to assay the flux and poise of the partial reactions, including those of excitation delivery, electron transfer, the proton gradient and the metabolic acceptor pools, under the steady state conditions pertaining at maximal photosynthetic rates.
www.life.uiuc.edu /crofts/ahab/instrev.html   (596 words)

  
 looking for electron transport chain   (Site not responding. Last check: 2007-11-07)
Electron Transport Chain Definition: Biomolecular machinery present in prokaryotic membranes and eukaryotic mitochnodria that couples the flow of electrons to proton pumps in order to convert energy...
The electron transport chain couples the transfer of an electron from NADH to molecular oxygen (O2) with the pumping of protons (H+) across a membrane.
Electron Transport Chain The electron transport chain is located predominantly in the: A. Outer membrane of the mitochondria B. Intermembrane space of the mitochondria C. Inner membrane of the...
www.foto-ophelia.de /electron_transport_chain.html   (315 words)

  
 FEBS Abstract
For this function, p66Shc utilizes reducing equivalents of the mitochondrial electron transfer chain through the oxidation of cytochrome c.
Redox-defective mutants of p66Shc are unable to induce mitochondrial ROS-generation and swelling in vitro, and to mediate mitochondrial apoptosis in vivo.
These data demonstrate the existence of alternative redox reactions of the mitochondrial electron transfer chain, which evolved to generate pro-apoptotic ROS in response to specific stress-signals.
www.blackwellpublishing.com /febsabstracts2005/abstract.asp?id=41123   (206 words)

  
 exam2
A new compound isolated from mitochondria is claimed to represent a previously unrecognized carrier in the electron transfer chain.
During oxidative phosphorylation, the proton motive force that is generated by electron transport is used to: A) oxidize NADH to NAD+.
Diagram the path of electron flow from NADH to the final electron acceptor during oxidative phosphorylation in mitochondria.
mason.gmu.edu /~mcoss/483/exam3.htm   (2380 words)

  
 Oxidative Phosphorylation: Chemiosmotic Coupling
The respiratory chain is embedded in cristae of the
At right is an electron micrograph, provided by Dr. Carmen Mannella of the Wadsworth Center, of a Neurospora mitochondrion in a frozen sample in the absence of fixatives or stains that might alter the appearance of internal structures.
are transferred from NADH to coenzyme Q within the respiratory chain complex I.
www.rpi.edu /dept/bcbp/molbiochem/MBWeb/mb1/part2/oxphos.htm   (1536 words)

  
 CyberEd® PLATO Science :: Science Education Software
State the location within a mitochondrion of the electron acceptors of the electron transfer chain.
Describe how the reduced coenzymes NAD and FAD carry hydrogen ions, electrons and their associated energy from the intermediates of the respiratory pathway to the electron transfer chain.
Students view a simple animation of the electron transfer chain (ETC) that shows the transfer of electrons from reduced NAD and reduced FAD to successive electron carriers in the mitochondrial membrane, and their final acceptance by oxygen.
www.cybered.net /commerce.asp?CatId=310&ProdId=X5002112   (445 words)

  
 Another Unusual Type of Citric Acid Cycle Enzyme in Helicobacter pylori: the Malate:Quinone Oxidoreductase -- Kather et ...
The quinones are subsequently oxidized by the electron
of the electron transfer chain are inactivated during membrane
Characterization of the respiratory chain of Helicobacter pylori.
jb.asm.org /cgi/content/full/182/11/3204   (3857 words)

  
 THE ELECTRON TRANSPORT CHAIN
The oxidation of NADH occurs in a stepwise manner involving an electron transport chain.
A small portion of the ubiquinone is tightly bound to ETC proteins and the rest is free to diffuse around in the membrane - the so-called ubiquinone pool.
In Mitchell's original Z-scheme the ETC is arranged in a series of loops with hydrogen carriers (A and C) facing the inside of the bacterial cell or mitochondrion and electron carriers (B and D) facing outwards.
www.science.siu.edu /microbiology/micr425/425Notes/07-Respire.html   (3207 words)

  
 [No title]
The electrons are donated by another protein that binds briefly to the P450 and passes an electron from a prosthetic group.
This handoff of electrons between proteins is called an electron transfer chain, and it is similar to the electron transfers that go on in complexes I to IV of the electron transfer chain in mitochondria.
NADPH is the source of electrons that flow from ferredoxin reductase to ferredoxin and then to P450.
drnelson.utmem.edu /P450lect.html   (4610 words)

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