Enzymes--Kinetic Role of the Enzyme
Terms
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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.