Electron Transport Chain

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Electron Transport Chain

The first step in the electron transport chain process is for the NADH2 produced during glycolysis, the intermediate step, and the citric acid cycle to be attracted to Complex I (FMN ·FeS)due to its high affinity for NADH2. This attraction pulls NADH2 to Complex I (NAD dehydrogenase) and the two electrons from H2 are pulled off by the FeS (ferrous sulfate) leaving two H+ ions and NAD+. These molecules repel each other and this results in the NAD+ being recycled. The hydrogens remain in the matrix while the two electrons are attached to Complex I. This attachment activates the pump by changing its shape and then actively transports the hydrogens to the intermembrane space. The electrons on Complex I are highly attracted to cytochrome Q (ubiquinone– carrier cyt Q) because cyt Q ·FeS has an even higher affinity for the electrons than Complex I. The electrons move to cyt Q as they are attractively pulled by the FeS. As the electrons move to cyt Q, they are immediately attracted to Complex III (cytochrome reductase – cyt bc1), which has an even higher affinity for the electrons than cyt Q. The electrons move to Complex III, changing its shape which activates the pump and two hydrogens are actively transported to the intermembrane space while the electrons remain at Complex III. Then, cytochrome C (carrier cyt c) has a higher affinity for these electrons and therefore the electrons move to cyt C. Complex IV (cytochrome oxidase) has an even higher affinity for electrons than cyt C, so the electrons move immediately to Complex IV and activate the pump, which actively transports two hydrogens to the intermembrane space. The last electron acceptor in the chain is O2. The hydrogens in the intermembrane space begin to fall down the gradient and diffuse through ATP synthase allowing it to bind with its substrates ADP and phosphate to produce ATP. During this process, two hydrogens diffuse through, and they are attracted to the O2, binding...
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