Module 1- ATP is the universal currency of free energy Flashcards
what are the three reason organisms require continual input of energy
-the performance of mechanical work, such as muscle contraction and cellular movement
-the active transport of biomolecules and ions
-the synthesis of macromolecules form a simple precursors
where is the free energy captured form for the 3 major purposes organisms require continual inputs of energy
it is captured from the environment. phototrophs (plants) use photosynthesis, chemotrophs (humans) obtain ATP through oxidation of carbon fuels such as carbohydrates
how do enzymes effect chemical reactions
they only speed it up. they dont change equilibrium
when can reaction take place spontaneously
only when delta G is negitive
in enzymes what does the free energy difference (delta G) determine
weather a reaction will take place spontaneously
what are the two thermodynamic properties of a reaction you need to consider to understand how enzymes work
-the free energy (delta G) between the product and the reactants
-the free energy required to imitate the conversion of the reactants to products
what happens when a system is at equilibrium
there is no net change in concentrations of products and reactants (delta=0)
when can reactions with a + delta G take place
only with an input of energy, often involving ATP cleavage
what does the delta G provide us information on
only weather a reaction can occur spontaneously. delta G is independent of the path whereby the reactants are converted to products , but only free energy of products minus the free energy of the reactants
what does the free energy determine in enzyme reactions
the rate at which the reaction will proceed. it is later that the enzyme effects it
how are thermodynamically processes even possible
two or more reactions can be coupled together, when this occurs the delta G changes that occur for each one are additives. as long as the overall free energy changes for the reactions is negative then the process will occur spontaneously
when it comes to metabolism what is the most common “currency” used
ATP. its not only in mammals but in most living organisms
what other less common nucleoside triphosphates are energy rich and can sometimes be used as free energy donors
GTP, UTP, CTP
what are the energy bonds in ATP
acid anhydride bonds. they are two acid groups that lose a water molecule upon formentation
what is so special about ATP that it is used as the carrier of energy in the cell
-it has high phosphoryl-transfer potential, meaning it readily transfers its phosphate group to water
-the standard free energy of hydrolysis of ATP where terminal phosphate group is cleaved to make ADP and inorganic phosphat (Pi) is very negative at -30.5KJ/mol
explain the increasing entropy going from ATP to ADP
hydrolysis of ATP results in two molecules instead of a single ATP molecule, thus increasing the entrophy
explain the change in resonance stabilization going from ATP to ADP
Pi one of the products of hydrolysis has agreater resonance stabalization than any of the phosphates in ATP
in ATP what is the reason for the large standard free energy change of product and reactants
-electrostatic repultion
-resonance stability
-increased entropy
-stabilization of hydration
explain the change in electrostatic repulsion going from ATP to ADP
at pH of 7 ATP carries four - charges which repel on and other when they are in close proximity. when ATP is hydrolyzed the electrostatic repulsion is reduced
explain the change in stabilization by hydration going from ATP to ADP
water binds to ADP and Pi which stabilizes these molecules and makes the reverse reaction less favorable
what is pyrophosphate
sometime ATP is hydrolyzed in a way that releases a pyrophosphate. which is two phosphate groups joined together. this results in AMP as the product
-results in a large about of energy (-45.6KJ/mol)
why is ATP an intermediate among biologically important phosphorylated molecules
its phoshphoryl-transfer potential is high and it not only allows ATP to donate its P group but to also accept phosphate groups from other certain molecules. it is both able to give and receive a P group
