31March2009NutritionMetabolismPosting

31March2009NutritionMetabolismPosting - Summary: 2 ways to...

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2 ADP 2 ATP 2 ADP 2 ATP + 2 Pi SLP SLP Summary: 2 ways to make ATP in cells 1. SLP in Glycolysis and recovery of NAD + in fermentation: 6C 2(3C-P) 2(P-3C-P) 2(3C-P) 2(3C) 2 ATP 2 ADP 2 NAD + 2(NADH+H + ) derivative 2 (3C) In glycolysis an organic molecule (6C) is phosphorylated, broken into 2 (3C) molecules. The 2 (3C) molecules are oxidized and phosphorylated; in the process 2NAD + are reduced to 2 (NADH+H + ). The Pi’s were transferred by SLP to 2 ADP to make 2 ATP. Fermentation is how the 2 NAD + are eventually recovered for continuing glycolysis. fermentation
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Summary: 2 ways to make ATP in cells 1. SLP in Glycolysis and recovery of NAD + in fermentation: Only 2 net ATP are made during glycolysis - not much! For some chemoheterotrophic bacteria, this is the only way to make ATP, but they can do it efficiently. They can also live in anaerobic environments (where there is no O 2 ). How do we know? (Note that there is no O 2 in the reaction shown above!)
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2. Chemiosmotic synthesis is the other mechanism cells use to make ATP. Chemiosmotic synthesis is used by phototrophs, chemolithotrophs and some chemoheterotrophs. 3 parts to consider: a. The ATPase - how to make ATP using a proton gradient? b. How passing electrons through a series of proteins (the electron transport chain) can create a proton gradient. c. Where do the electrons that get passed come from? Parts a and b are roughly the same in phototrophs, chemolithotrophs and chemoheterotrophs. Part c is what differentiates them.
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The ATPase = ATP synthase For chemiosmotic synthesis, the concentration of protons differs inside and just outside the cytoplasmic membrane of bacteria or inner membrane of mitochondria and chloroplasts. It takes work to push the protons out across the membrane. Then, if these protons pass from the outside to the inside, the process can release energy (to do work). The cell could let protons flow back through the membrane and harness some of the energy that was used to make the gradient. The protons flow back in through a complex of proteins called the ATP synthase or the ATPase.
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The ATPase = ATP synthase Protons require a “permease” to let them through the membrane: the ATPase does that function. The ATPase does double duty: It has a channel for H + to move through from the outside toward the inside, and (entry channel, exit channel) it can bind ADP and PO 4 3– and phosphorylate the ADP. As the proton passes through the ATPase, part of the complex
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This note was uploaded on 11/03/2009 for the course ECON 210 taught by Professor James during the Spring '09 term at The University of British Columbia.

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31March2009NutritionMetabolismPosting - Summary: 2 ways to...

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