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27 Cards in this Set

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Most cellular rxns are slowed by a lg barrier called ____.
energy of activation (E.a)
Role of the enzyme is to open the nearly-closed ____ created by the ___ and allow a reaction to proceed more easily.
gate .......E.a
Thermodynamics is the study of _____.
energetics of chem. rxns
The 2 relevant forms of energy are ____ & ______.
heat energy (movement of molecules) and potential energy (stored in chemcl bonds)
The most imp. energy storage molecule in all cells is ___.
ATP (in ester bonds bet. phosphate grps.)
ATP has high-energy ______ bonds between its _____ groups.
ester bonds bet. phosphate grps.
the first law of thermodynamics is also called ______.
the law of conservatn of energy
1st law of thermodynamics states ____.
the amt. of energy in the universe is constant
2nd law of thermodynamics states ___.

Its major implication for chem. is that ___.
disorder/entropy in the universe tends to incresase.

implies: a rxn will occur spontaneously only if it incrses the entropy in the universe.
ΔS = _____

a negative ΔS means ____.
S.f - S.i

a -ΔS means the system lost entropy, disorder decreased, it's a non-spontaneous rxn
Gibbs' free energy is a practical way to discuss _____.
thermodynamics
formula for Gibbs' free energy
ΔG = ΔH - TΔS

free e. = enthalpy change - temp.(entropy change)
TΔS = ___
(temp.)(change in enthalpy)
ΔH = ___
change in enthalpy = ΔE - PΔV

E = bond energy of prodcts/reactants
P = pressure
V = volume
consider ΔH = ΔE - PΔV.
since cellr rxns take place in liquid phase, how is H rel. to E in a cell?
H approximates E since the ΔV is negligible.
ΔG incr. with incrsg. ____ or decrsgn. ___
proprtnl to ΔH(bond energy)

inversely prop. to S (entropy)

....bond energy goes up, more free energy....disorder goes up, less free energy

more S, less G
negative G = favorable rxn
ΔG determines if rxn is ___ or ___.
favorable or unfavorable

spont. rxns th/hapen w/o a net addtn of energy have ΔG<0. they're EXERGONIC
endergonic rxns occur only when ___.

this occurs by ____ in the body.
energy is added.

rxn coupling drives 'em in body
rxns with a -ΔH are ___.
exergonic/favorable/spontaneous

they give off heat.
exothermic = ___
exergonic/favorable/spontaneous
endothermic = ___
endergonic/unfavorable/non-spontaneous
How do homeotherms maintain body temp?
via metabolic rxns, which are mostly exothermic
-ΔG means what?
the system goes to a lower free e. state

...and a sys. will always move in the dir. of lowest free e.(G)
a non-spontaneous rxn requires ___
energetic input
If the p's in a rxn have more entropy (S) than the r's, and the enthalpy (H) of both is the same, is it spontaneous?
yes, cuz

ΔG= ΔH-TΔS

this would give a negative ΔG, indicatng a spont. rxn
ΔG dep. on []s of ___.
p's and r's

so, standard free e. change is used, ΔG.0---p's and r's at 1M
ΔG at pH 7 =
ΔG.0' = -RTlnK.eq'

Keq' is the equilbrm constant for a rxn = ratio of p's and r's at eq.