THE ELECTRON TRANSPORT CHAIN AND CHEMIOSMOSIS
In most cases the proton motive force is generated by an electron transport chain which acts as both an electron and proton pump, pumping electrons in opposite directions, creating a separation of charge. In the mitochondria, free energy released from the electron transport chain is used to move protons from the mitochondrial matrix to the intermembrane space of the mitochondrion. Moving the protons to the outer parts of the mitochondrion creates a higher concentration of positively charged particles, resulting in a slightly positive, and slightly negative side (then electrical potential gradient is about -200 mV (inside negative). This charge difference results in an electrochemical gradient. This gradient is composed of both the pH gradient and the electrical gradient. The pH gradient is a result of the H+ ion concentration difference. Together the electrochemical gradient of protons is both a concentration and charge difference and is often called the proton motive force (PMF). In mitochondria the PMF is almost entirely made up of the electrical component but in chloroplasts the PMF is made up mostly of the pH gradient. In either case the PMF needs to be about 50 kJ/mol for the ATP synthase to be able to make ATP.
The membrane electron transport chain and chemiosmosis is a ..
The electron transport chain takes electrons from reduced electron carriers (NADH) and passes them to a terminal electron acceptor (O2), and uses the free energy released to generate a membrane proton gradient. Note that the ATP synthase is not part of the electron transport chain, but is shown here because it uses the proton gradient to power ATP synthesis. The ETC builds up the proton gradient, while the ATP synthase discharges the proton gradient in the process of making ATP.
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Photosynthesis: NADPH carries e- from light reaction to Calvin cycle
Cellular Respiration: NADH, FADH2 carry e- from glycolysis/Krebs cycle to electron transport chain
an electron transport chain pumps H+ ions in the ..
Cellular energy metabolism features a series of redox reactions. Heterotrophs oxidize (take electrons from) organic molecules (food) and reduce (give them to) an electron carrier molecule, called NAD+ (in the oxidized form) that accepts electrons from food to become NADH (the reduced form). NADH then cycles back to NAD+ by giving electrons to (reducing) the first complex of the membrane electron transport chain. Thus NAD+/NADH is a key intermediary in shuttling electrons from food molecules to the electrons transport chain for respiration.
Electron transport and ATP synthesis during photosynthesis".
Organisms that use cellular respiration, such as humans, use that oxygen to kick-start and propel the reactions of cellular respiration, especially those occurring during the Electron Transport Chain.
Electron Transport Chain and Chemiosmosis Flashcards …
We define respiration as the passage of electrons down the electron transport chain. We breathe (respire) oxygen because oxygen is the terminal electron acceptor, the end of the line for our mitochondrial electron transport chain. The video below shows the details of the electron transfer reactions, and how they are coupled to pumping protons across the membrane. This is a form of active transport, because the electron transfers release free energy that is used to pump protons against their concentration gradient.
Electron Transport Chain & Chemiosmosis - SBI4U …
Bacteria can modify their electron transport chains to use a variety of electron donors and electron acceptors, and will switch to the best available in their environment. In marine sediments, microbial communities stratify according to redox potential. The deeper, more anoxic layers use electron acceptors with progressively lower reducing potential.
the electron transport chain and chemiosmosis make up ..
We have seen how ATP synthase acts like a proton-powered turbine, and uses the energy released from the down-gradient flow of protons to synthesize ATP. The process of pumping protons across the membrane to generate the proton gradient is called . Chemiosmosis is driven by the flow of electrons down the electron transport chain, a series of protein complexes in the membrane that forms an electron bucket brigade. Each of these protein complexes accepts and passes on electrons down the chain, and pumps a proton across the membrane for each electron it passes on. Ultimately, the last complex in the electron transport chain passes the electrons to molecular oxygen (O2) to make water, in the case of aerobic respiration.