chapters_13_14_15_outline2_spr09

chapters_13_14_15_outline2_spr09 - cytoplasmic membrane...

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Aerobic respiration In aerobic respiration, the pair of electrons from NADH is passed through a series of intermediates to oxygen NADH is oxidized back to NAD+, oxygen is reduced to water Oxygen is the terminal electron acceptor There are several types of intermediates that pass electrons from NADH to oxygen (can’t go straight there, must have middlemen): flavoproteins cytochromes quinones iron-sulfur proteins These components make up an electron transport chain (ETC) In prokaryotes, the ETC is in the cytoplasmic membrane In eukaryotes, the ETC is in the mitochondria Electron transport chain- series of membrane associated electron carriers that carry electrons from the primary electron donor to the terminal electron acceptor During electron transfer, electron transport systems conserve some of the released energy for the synthesis of ATP Electron transport chain Different organisms have different ETC Some have more than one for different growth conditions Electrons are passed from one compound to the next At each step, some energy from the electrons is used to push hydrogen ions across the cytoplasmic membrane into the periplasm or to outside of CM cytoplasm cytoplasmic membrane periplasm NADH + H + NAD + 2e - 2e - 2H + 2e - 2e - 1/2 O 2 H 2 O iron- sulfur protein quinone Cyt b Cyt o H + 2H + flavoprotein
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Hydrogen ion gradient/proton motive force/chemiosmosis This creates a hydrogen ion gradient across the cytoplasmic membrane Outside of CM is now more acidic and more + then the cytoplasm This gradient is a source of potential energy ATPase ATPase- enzyme which adds a phosphate group to ADP to make ATP ATPase does this by allowing protons to cross back into the cytoplasm Energy is released by reducing the hydrogen ion gradient, this energy is used to make the high energy bond of ATP. Oxidative phosphorylation- process of using the hydrogen ion gradient to make ATP Glycolysis,> krebs,> and electron transport (all go together.) Substrate-level vs. Oxidative Phosphorylation Substrate-level phosphorylation ATP is made by transferring a high energy phosphate group to ADP Oxidative phosphorylation Energy from a hydrogen ion gradient is used to make ATP (substrate level-phos =glycolysis) (anaerobic resp. = substrate level and oxidative) (fermentation=substrate-level phos.) Respiration and Fermentation summary Fermentation- glucose to pyruvate to fermentation products-electrons from NADH used to reduce pyruvate. Net 2 ATP/glucose cytoplasm periplasm H + H + H + H + H + H + H + H + ATPase ADP + P i ATP H +
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Respiration- glucose to pyruvate then pyruvate is oxidized to CO2 in TCA cycle- electrons from NADH are transferred to oxygen through ETC. Up to 38 ATP/glucose. Anaerobic respiration
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chapters_13_14_15_outline2_spr09 - cytoplasmic membrane...

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