BIO LAB REVIEW!! - Exercise 7: Cellular Metabolism...

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Exercise 7: Cellular Metabolism Catabolic Pathways : biochemical reactions that break down complex molecules in order to release energy that the cell can use Glycolysis Fermentation The Krebs or Citric Acid Cycle The Electron Transport Chain / ATP Synthase 1) Glycolysis: Important characteristics of this cycle: It’s anaerobic Occurs in the cytoplasm Products= (2) net ATP and (2) Pyruvate For organisms that live in anaerobic environments, glycolysis may be responsible for most ATP production NAD + may be a limiting factor in these reactions 2) Fermentation: Cells need to have a mechanism for replenishing their supply of NAD + in order to continue glycolysis. This set of reactions is called fermentation . Fermentation has the limitation of making toxic products Lactic acid fermentation a Ex. animal cells Alcohol fermentation (Ethanol + CO 2 ) a Ex. brewers’ yeast Again, this process occurs in the cytoplasm . 3) The Krebs or Citric Acid Cycle: We could just stop at glycolysis… or continue on with some of our Pyruvate to squeeze more energy out of our original glucose molecule. Krebs Cycle Occurs: In the presence of O 2 (aerobic ) In the mitochondria (of both plants AND animals) Products: (8) NADH (2) FADH 2 (2) ATP 4) The Electron Transport Chain/ ATP Synthase: While we still haven’t produced a large number of ATP molecules, we have produced several reduced molecules (NADH and FADH 2 ) These reduced molecules feed into the Electron Transport Chain of reactions Again, these reactions require the presence of O 2 and they occur in the mitochondria. The Electron Transport Chain is responsible for setting up a high concentration of H + in the mitochondrial intermembrane space . Separated from the matrix by the inner membrane H + gradient is established through a series of oxidation / reduction reactions The final electron acceptor is oxygen .
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ATP Synthase H + ions are allowed to pass back through the inner membrane through the enzyme, ATP synthase (via diffusion ). This process allows the enzyme’s active sites to catalyze the reaction: ADP + P i = ATP Produces 32-34 ATP per glucose molecule! Experiment 1- Under anaerobic conditions, yeasts produce alcohol and CO 2 through glycolysis and fermentation . CO 2 Production Demo You will be testing the requirements of yeast for fermentation to occur. We will test the sugar requirements for fermentation. Different sugars to be tested: Glucose, Fructose, Sucrose, Starch We will conduct the experiments in fermentation vials . The rate of fermentation will be determined by how many mm of space CO 2 is occupying in the tube Experiment 2- TTC (tetrazolium) is a chemical indicator that changes from clear to red when it is reduced . In the presence of an
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This note was uploaded on 03/28/2008 for the course BIOL 112 taught by Professor Vaughn during the Spring '08 term at Texas A&M.

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BIO LAB REVIEW!! - Exercise 7: Cellular Metabolism...

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