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Unformatted text preview: Megan Lewis [email protected] OH Thursday 12pm York 3010B Handout 2 Last of enzyme calculations, YAY!! + ΔG A←B ΔG A →B • The ___________ negative the ΔG, the more products formed. • In order to make the rxn favor products over reactants you must couple a rxn with a ΔG that is a large enough negative value so that when you add it to the ΔG of A →B the overall final ΔG is negative. Ex : hydrolysis of ATP → ADP + Pi gives a ΔG=30.5kJ/mol If the ΔG of A→B is <30.4kJ/mol then the final ΔG will be less than 0 and thus exergonic. • Our body, and in all organisms in fact, have created a “cash” value in Pi. Every Pi that is released from a molecule releases with it energy since Pi actually wants to be free from other molecules. Thus, the ΔG for releasing Pi is a negative value since the production of free Pi is favored over Pi being attached to a molecule such as ATP. • By coupling this exergonic, product favoring rxn with the endergonic, reactant favoring rxn, the 2 ΔG’s are summed and total a new ΔG. If this new number is negative, then reactions of A →B and ATP → ADP + Pi occur since the overall rxn becomes exergonic. • By using ATP’s hydrolysis (breakdown into ADP and Pi) as the coupler, the ΔG becomes negative resulting in the production of B. And in fact, the B to A ratio increases by a factor of ________ . No matter the ’s, as long as the final ΔG value is negative, the product with be produced by a ________ fold increase! • While ATP hydrolysis gives a ΔG of 30.5kJ/mol, the actual ΔG within a cell is between ______ and ________ kJ/mol since the [ATP] is held steady between 500 and 5000 for every [ADP] in each cell. Thus, 47kJ/mol is the minimum amt of energy needed for a cell to remain alive (to allow all of its processes to have enough energy to occur)....
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 Spring '08
 Price
 Biochemistry, Cellular Respiration, Glycolysis, Adenosine triphosphate, excess ATP

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