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27 Cards in this Set
- Front
- Back
Most cellular rxns are slowed by a lg barrier called ____.
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energy of activation (E.a)
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Role of the enzyme is to open the nearly-closed ____ created by the ___ and allow a reaction to proceed more easily.
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gate .......E.a
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Thermodynamics is the study of _____.
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energetics of chem. rxns
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The 2 relevant forms of energy are ____ & ______.
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heat energy (movement of molecules) and potential energy (stored in chemcl bonds)
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The most imp. energy storage molecule in all cells is ___.
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ATP (in ester bonds bet. phosphate grps.)
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ATP has high-energy ______ bonds between its _____ groups.
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ester bonds bet. phosphate grps.
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the first law of thermodynamics is also called ______.
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the law of conservatn of energy
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1st law of thermodynamics states ____.
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the amt. of energy in the universe is constant
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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. |
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ΔS = _____
a negative ΔS means ____. |
S.f - S.i
a -ΔS means the system lost entropy, disorder decreased, it's a non-spontaneous rxn |
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Gibbs' free energy is a practical way to discuss _____.
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thermodynamics
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formula for Gibbs' free energy
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ΔG = ΔH - TΔS
free e. = enthalpy change - temp.(entropy change) |
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TΔS = ___
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(temp.)(change in enthalpy)
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ΔH = ___
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change in enthalpy = ΔE - PΔV
E = bond energy of prodcts/reactants P = pressure V = volume |
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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.
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ΔG incr. with incrsg. ____ or decrsgn. ___
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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 |
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ΔG determines if rxn is ___ or ___.
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favorable or unfavorable
spont. rxns th/hapen w/o a net addtn of energy have ΔG<0. they're EXERGONIC |
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endergonic rxns occur only when ___.
this occurs by ____ in the body. |
energy is added.
rxn coupling drives 'em in body |
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rxns with a -ΔH are ___.
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exergonic/favorable/spontaneous
they give off heat. |
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exothermic = ___
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exergonic/favorable/spontaneous
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endothermic = ___
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endergonic/unfavorable/non-spontaneous
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How do homeotherms maintain body temp?
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via metabolic rxns, which are mostly exothermic
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-ΔG means what?
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the system goes to a lower free e. state
...and a sys. will always move in the dir. of lowest free e.(G) |
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a non-spontaneous rxn requires ___
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energetic input
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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?
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yes, cuz
ΔG= ΔH-TΔS this would give a negative ΔG, indicatng a spont. rxn |
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ΔG dep. on []s of ___.
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p's and r's
so, standard free e. change is used, ΔG.0---p's and r's at 1M |
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ΔG at pH 7 =
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ΔG.0' = -RTlnK.eq'
Keq' is the equilbrm constant for a rxn = ratio of p's and r's at eq. |