lab 7 - Show safety slide here. Energetics To perform their...

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Unformatted text preview: Show safety slide here. Energetics To perform their many tasks, cells require transfusions of energy from outside sources In most ecosystems, energy enters as sunlight. Light energy trapped in organic molecules is available to both photosynthetic organisms and others that eat them. Organic molecules store energy in their arrangement of atoms (bonds) A cell breaks down these molecules to get energy with the help of enzymes This involves a series of oxidationreduction reactions Oxidation is the loss of electrons Reduction is the gain of electrons (becomes more negative) OIL RIG oxidation is loss, reduction is gain Enzymes are crucial in the transfer of electrons Coenzymes a non-protein molecule required for some enzymes to function Act as electron carriers Take part in the oxidation/reduction rxns NADH NAD+ FADH2 FAD ATP Adenosine triphosphate phosphate bonds are unstable & high energy Source of energy for most metabolic processes Cellular respiration A series of enzyme-mediated redox. rxns. that break C-C and C-H bonds (in organic molecules) to release energy and store it as ATP Respiration occurs in steps Glycolysis Fermentation (if no oxygen present) Glycolysis Kreb's cycle, PDC & ETC (if oxygen is present) Glycolysis ("Gly"= sugar/ "lysis"= break) Pathway is billions of years old. Breakdown of sugar (glucose) Occurs in cytoplasm May occur with or without oxygen Produces pyruvate (x2 per glucose) Occurs in prokaryotes and eukaryotes Fermentation Occurs in cytoplasm Anaerobic (no oxygen present) Prokaryotes, plants and animals Two possible products in addition to CO2 Lactic acid fermentation Ex. In muscles Alcohol fermentation (A pt 4) Ex. Yeast/wine Doesn't produce much ATP, but recycles NAD+ for use in glycolysis again Today's Experiment: Yeast combined with one of the following Glucose Sucrose Yeast boiled and sucrose Water Measuring the amount of CO produced by Kreb's Cycle Occurs in mitochondrial matrix (of eukaryotes) Aerobic (oxygen present) Occurs in cytoplasm of bacteria (remember....bacteria do NOT have mitochondria but they still need to make ATP!!) Purpose is to gather electrons for ETC Uses both enzymes and coenzymes Overall reaction of Respiration C6H12O6 + 6O2 6CO2 + 6H2O + energy(ATP) Kreb's cycle (Today's Experiment): Enzyme: succinic dehydrogenase (in lima bean juice) Substrate: succinate Product: fumarate In the transformation of succinate to fumarate, FAD is the electron acceptor. We are using DPIP instead. DPIP starts blue, as it gains electrons (reduced) it becomes colorless Absorbance will lower when product is forming Enzymes are used in the Kreb's cycle Inhibitors Prevents enzyme form working Competitive- a molecule that competes for the active site of an enzyme (ex. malonate) Non-competitive inhibitor- binds to another part of the enzyme changing the shape of the enzyme and making the active site nonfunctional (ex. cyanide) ETC electron transport chain Occurs in the cristae (inner mitochondrial membrane) of mitochondria (in plants and animals) Occurs in plasma membrane of bacteria Electrons are passed from one component of the E.T.C. to the next and protons are also pumped (parts of the E.T.C. are proton pumps) from mitochondrial matrix to the inter-membranous space of the mitochondria. Protons then return to the matrix but must pass through an enzyme called ATP Synthase. This activates ATP Synthase (which adds a phosphate to ADP.....producing ATP once again). Oxygen is the final electron acceptor at the end of the E.T.C. creating water......this is why we breathe!!! Clean up Wash all test tubes Clean petrie dishes Wash cutting board Turn off spec Clean fermentation vials Line up bottles ...
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This note was uploaded on 11/11/2008 for the course BIOL 111 taught by Professor Rizzo during the Fall '07 term at Texas A&M.

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lab 7 - Show safety slide here. Energetics To perform their...

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