Topic11.pdf - Topic 11 Oxidative Phosphorylation Readings pp.149-150 438 447-469 By the end of this topic you should be able to • Describe the five

Topic11.pdf - Topic 11 Oxidative Phosphorylation Readings...

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Topic 11 Oxidative Phosphorylation Readings pp.149-150, 438, 447-469 Overview In the citric acid cycle, two carbons are oxidized to CO 2 to reduce the electron carriers NAD + and FAD to NADH and FADH 2 , respectively. The electrons carried by NADH and FADH 2 are delivered to O 2 through many intermediates in the electron transport chain, the components of which are embedded in or associated with the inner mitochondrial membrane. The energy released by these oxidation/reduction reactions is used to pump protons (H + ions) out of the matrix and into the intermembrane space (Fig 14-11, p.454). The electrochemical gradient thus established is used to synthesize ATP. This process of transferring electrons from one carrier to another to form ATP is called oxidative phosphorylation . We will first consider electron transport in the mitochondrion. Mitochondrial electron transport system The mitochondrial electron transport system contains four large protein-based complexes that work in sequence to deliver electrons to oxygen (Fig 14-14, p.456, Movie 14.2). Each complex contains an enzyme that catalyzes electron transfer, and several non-protein groups that accept and release electrons. (Non-protein chemical groups that give proteins functional capabilities not provided by amino acids are called cofactors. A cofactor may be tightly bound to a protein, in which case the cofactor is called a prosthetic group, or it may interact with proteins transiently.) Three of the complexes in the electron transport system contain protein subunits that enable movement of protons across the membrane. There are many electron carriers at work in the electron transport chain. Electrons pass from one carrier to the next in a strictly defined order, from a carrier with relatively low electron affinity to one with higher affinity (Fig 14-24, p.467). A carrier's electron affinity is determined by its chemical structure and by the environment surrounding it. The five By the end of this topic, you should be able to: Describe the five types of electron carriers found in the mitochondrial electron transport chain Explain how electrons flow between complexes of the electron transport chain, and ultimately to O 2 State how many protons are pumped out of the matrix for each reduced electron carrier that donates electrons to the electron transport chain Explain how energy flows from reduced electron carriers to ATP in the process of oxidative phosphorylation Explain the fundamental mechanism of ATP synthase, without memorizing the roles of individual subunits State the number of protons that move across the inner mitochondrial membrane to synthesize and export one ATP molecule, and justify that number Calculate how much ATP can be obtained by aerobic or anaerobic metabolism of one molecule of glucose Predict the effects of inhibiting elements of the oxidative phosphorylation system
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