B I O L O G Y 0 2 330-Dec-09Gardiner1ATP and EnzymesCurrency and Banking MachinesChapter 4Fig. 4.5Fig. 4.5Answer:Answer:•Works by thedirect chemical transferdirect chemical transferof a phosphate groupphosphate group.•This is called“phosphorylationphosphorylation”.• The exergonicexergonichydrolysishydrolysisof ATPATPis coupled with the endergonicendergonicprocessesprocessesby transferringtransferringaphosphate groupto another molecule.B I O L O G Y 0 2 330-Dec-09Gardiner5•Transfer phospate group from ATP to another molecule, change its free energy so that what was an endergonic ("uphill") reaction becomes an exergonic ("downhill") reaction.•This is called energy coupling. Hydrolysis ofHydrolysis ofATPATP•ATP+ H2O→ADP+ P(exergonic)Hydrolysis(add water)PPPAdenosine triphosphate(ATP)PPP+Adenosine Adenosine diphosphatediphosphate(ADP)(ADP)Fig. 4.12
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Dehydration ofDehydration ofATPADP + P →ATP+ H2O (endergonic)Dehydration synthesisDehydration synthesis(remove water) (remove water) PPPAdenosine Adenosine triphosphatetriphosphate(ATP)(ATP)PPP+Adenosine diphosphatediphosphate(ADP)(ADP)Fig. 4.12B I O L O G Y 0 2 330-Dec-09Gardiner8Chemistry in Cell• Factory-send chemicals through pipes, valves, computer program-complex, hard to miniaturize• Cell– Reactants and products in same space– Chemicals interact by random collisions•Total space must be smallB I O L O G Y 0 2 330-Dec-09Gardiner9Enzymes•A spontaneous chemical reaction may occur very slowly•Enzymes speed up reactions•A catalyst is a chemical agent that changes the rate of a reaction without being consumed by the reaction –enzymes are catalytic proteinsB I O L O G Y 0 2 330-Dec-09Gardiner10Enzymes•In every chemical reaction between molecules bonds must be broken [requires energy] (E) and bonds must be made (releases E)•The initial energy required to break bonds is the activation energy (EA