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Week 1, Lecture 2, ATP and Enzymes

Week 1, Lecture 2, ATP and Enzymes - Answer BIOLOGY ATP and...

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B I O L O G Y 0 2 3 30-Dec-09 Gardiner 1 ATP and Enzymes Currency and Banking Machines Chapter 4 Fig. 4.5 Fig. 4.5 Answer: Answer: Works by the direct chemical transfer direct chemical transfer of a phosphate group phosphate group . This is called phosphorylation phosphorylation” . • The exergonic exergonic hydrolysis hydrolysis of ATP ATP is coupled with the endergonic endergonic processes processes by transferring transferring a phosphate group to another molecule. B I O L O G Y 0 2 3 30-Dec-09 Gardiner 5 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 of Hydrolysis of ATP ATP ATP + H 2 O ADP + P (exergonic) Hydrolysis (add water) P P P Adenosine triphosphate (ATP) P P P + Adenosine Adenosine diphosphate diphosphate (ADP) (ADP) Fig. 4.12
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Dehydration of Dehydration of ATP ADP + P ATP + H 2 O (endergonic) Dehydration synthesis Dehydration synthesis (remove water) (remove water) P P P Adenosine Adenosine triphosphate triphosphate (ATP) (ATP) P P P + Adenosine diphosphate diphosphate (ADP) (ADP) Fig. 4.12 B I O L O G Y 0 2 3 30-Dec-09 Gardiner 8 Chemistry 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 small B I O L O G Y 0 2 3 30-Dec-09 Gardiner 9 Enzymes 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 proteins B I O L O G Y 0 2 3 30-Dec-09 Gardiner 10 Enzymes 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 (E A