Module 1- ATP is the universal currency of free energy

Question 1

what are the three reason organisms require continual input of energy

Answer 1

-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

Question 2

where is the free energy captured form for the 3 major purposes organisms require continual inputs of energy

Answer 2

it is captured from the environment. phototrophs (plants) use photosynthesis, chemotrophs (humans) obtain ATP through oxidation of carbon fuels such as carbohydrates

Question 4

how do enzymes effect chemical reactions

Answer 4

they only speed it up. they dont change equilibrium

Question 4

when can reaction take place spontaneously

Answer 4

only when delta G is negitive

Question 4

in enzymes what does the free energy difference (delta G) determine

Answer 4

weather a reaction will take place spontaneously

Question 4

what are the two thermodynamic properties of a reaction you need to consider to understand how enzymes work

Answer 4

-the free energy (delta G) between the product and the reactants
-the free energy required to imitate the conversion of the reactants to products

Question 4

what happens when a system is at equilibrium

Answer 4

there is no net change in concentrations of products and reactants (delta=0)

Question 4

when can reactions with a + delta G take place

Answer 4

only with an input of energy, often involving ATP cleavage

Question 4

what does the delta G provide us information on

Answer 4

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

Question 4

what does the free energy determine in enzyme reactions

Answer 4

the rate at which the reaction will proceed. it is later that the enzyme effects it

Question 4

how are thermodynamically processes even possible

Answer 4

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

Question 4

when it comes to metabolism what is the most common “currency” used

Answer 4

ATP. its not only in mammals but in most living organisms

Question 5

what other less common nucleoside triphosphates are energy rich and can sometimes be used as free energy donors

Answer 5

GTP, UTP, CTP

Question 5

what are the energy bonds in ATP

Answer 5

acid anhydride bonds. they are two acid groups that lose a water molecule upon formentation

Question 5

what is so special about ATP that it is used as the carrier of energy in the cell

Answer 5

-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

Question 5

explain the increasing entropy going from ATP to ADP

Answer 5

hydrolysis of ATP results in two molecules instead of a single ATP molecule, thus increasing the entrophy

Question 5

explain the change in resonance stabilization going from ATP to ADP

Answer 5

Pi one of the products of hydrolysis has agreater resonance stabalization than any of the phosphates in ATP

Question 5

in ATP what is the reason for the large standard free energy change of product and reactants

Answer 5

-electrostatic repultion
-resonance stability
-increased entropy
-stabilization of hydration

Question 5

explain the change in electrostatic repulsion going from ATP to ADP

Answer 5

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

Question 5

explain the change in stabilization by hydration going from ATP to ADP

Answer 5

water binds to ADP and Pi which stabilizes these molecules and makes the reverse reaction less favorable

Question 5

what is pyrophosphate

Answer 5

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)

Question 6

why is ATP an intermediate among biologically important phosphorylated molecules

Answer 6

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