Bioenergetics And Thermodynamics Flashcards
how do u calculate change in free energy?
what determines the speed of a rxn?
activation energy
what does G tell us about the rate of the reaction?
NOTHING
why might adding heat to a rxn to speed it up not be smart?
it is non-specific
what is [s/p], pH, T and pressure at chemical standard conditions?
[ ] = 1M
PH = 0
T = 25 degrees C or 298 K
Pressure = 1atm
what does Keq and ΔG° measure?
the tendency for a rxn to proceed spontaneously
how do u calculate change in free energy of a rxn at eq?
where is a reaction proceeding from to?
from standard conditions to eq
what is [s/p], pH, T , [H2O] and [Mg2+] for biochemical standard conditions?
[s/p] = 1M
pH = 7
T = 25 degrees C or 298 K
[H2O] = 55.5M
Mg2+ = 1mM
if Keq > 1 what does this tell us abt the rxn?
(-) ΔG° = rxn will proceed forwards
if Keq < 1 what does this tell us abt the rxn ?
(+) ΔG° =rxn will proceed in the reverse
if Keq = 0 what does this tell us abt the rxn?
the rxn is at equilibrium ΔG° = 0
why is the Keq not used to determine actual free energy change?
becaused actual free energy change is rarely at equilibrium
what is the equation to determine actual free energy change
what does the actual free energy of a reaction depend on?
the [P] and [R]
what do we need to know in order to determine delta G’ at non-Eq conditions?
[ ] or ratios of P/R
what units must delta G’, R and T be in to use nernst equation?
Delta G’ = J/mol
R = J/mol -K
T = Kelvin
when can delta G’ at standard conditions be determined?
if you know [P/R] at equilibrium
what is needed for the energy released by an exergonic process to drive an endergonic process - and vice versa?
a common intermediate
what is the difference between direct and indirect coupling?
direct coupling uses the same enzyme to drive both reactions while indirect coupling uses 2 different enzymes
what is the delta G’ for the conversion of glucose to G6P (phosphorylation of glucose)?
~ -17 kj /mol
what is the delta G for the hydrolysis of ATP?
~ -30kj/mol
what is a common product of endergonic reactions that is also a common intermediate?
Pyrophosphate (PPi)
how much energy is released when breaking phosphoester bonds?
-16kj / molho
what makes ATP a metastable compound?
kinetically stable - high activation energy
thermodynamically unstable - high amount of energy released
what makes Mg2+ so important in metabolism?
Mg2+ and ATP have to bind together as a substrate
-Mg++ activates ATP