Intro Flashcards
if delta G = 0
you are at equilibrium
no work can be done
living systems are never at equilibrium
foundation of biochem
all living things adhere to chemical + physical laws of the universe
70% of living organisms is ___
water
H2O unique properties
polar, h-bonding, acid/base
thermal regulation
solvation in polar
1) break H-bonds & ionic bonds in NaCl
2) salt dissociates (inc. entropy)
3) make new H-bonds
delta H unchanged
solvation in nonpolar
entropy decreased b/c H2O forms highly ordered structure
amphipathic compounds
polar and nonpolar end
readily form ordered structures (ie. phospholipid bilayer)
inc. entropy of system by freeing up H2O
pH equation
-log [H+]
Ka equation
( [H+]x[A-]) / [HA]
pKa equation
-log(Ka)
stronger acids have…
high Ka
low pKa
unlike pH, pKa is _____
constant
pKa can be experimentally determined by …
titration
at midpoint of titration curve…
pKa = pH
this is 0.5 OH- equiv, 1.5 etc..
[HA] = [A-] at….
midpoint of titration curve
if pH < pKa
HA dominates
if pH > pKa
A- dominates
deprotonation
weak acid buffering range is
+- 1 from pKa
Henderson Hasselbach
pH = pKa + log( [A-] / [HA] )
to use Henderson Hasselbach
find initial moles (multiply L by M)
divide by total volume (L)
plug in
pKa can be used to tell you…
charge state of a molecule at a given pH
pI
isoelectric point (on an even # of OH-… 1, 2, 3 etc)
pH when a molecule is neutral
to find, average pKas surrounding neutral state
central dogma of molecular biology
info stored as DNA transcribed to RNA translated to protein
