Class 2 E1 Flashcards
standard state
about room temp
ΔG of rxn relies on ΔG 0 (free E at standard state cond’s)
RT and [products] and [substrates (reactants)]
standard state
For free E at standard state the higher [product] means?
more E is req’d.
For free E at standard state the larger your denominator the?
easier it is to move forward.
For free E at standard state the larger your denominator
the less E req’d.
ΔG
change in Gibbs free E.
ΔG naught
change in Gibbs free E of standard state.
ATP has a large
ΔG
ATP hydrolysis is a rxn used to?
drive other rxns forward
ADP is more stable than?
ATP
You phosphorylate what to make ATP?
ADP
Cells make their own ATP via?
ATP synthase
ATP hydrolysis has what type of ΔG?
positive
ATP is also
a nucleotide in RNA, can be incorporated into a long strand of mRNA.
Equilibrium
chemical state when forward rate equals reverse rate.
At equilibrium the net change of reactants and products is?
zero
Le Chatelier’s Principle states that
all rxns move toward equilibrium.
Equilibrium: the [reactants and products]
don’t need to be the same.
Equilibrium: more product =
rxn in reverse direction.
Equilibrium: more reactants / products =
rxn in forward direction.
Rxns are most favorable when?
they are at equilibrium.
Steady State
arrows same length in both directions.
If a rxn arrow is longer then
that direction is more favorable.
If a rxn arrow is shorter then
that direction is less favorable.
Equilibrium related to free E by?
Keq
Keq
equilibrium constant; defines relative conc’s of products and substrates.
If there’s no change in reactants or products there is no change in?
ΔG.
ΔG =
ΔG°+ RTln ([C]^c[D]^d/[A]^a[B]^b)
Keq =
[C]^c[D]^d/[A]^a[B]^b
Kinetics
analyzes rates of chemical rxns.
Kinetics can involve
single / multiple reactants (substrates) to make single / multiple products
Kinetics depends on
[products] and [reactants]
temperature
factors specific to individual rxn.
Kinetics: rates depend on
[products] and [reactants]
Enzymes reduce
activation E needed for a rxn.
Enzymes have a stabilized transition state by
donating e-‘s that enzyme will eventually recover back.
Rxn Rate
A + B → C
Rate = d[C]/dt= k[A][B]
For the rxn A + B → C, if A is halved, how does that affect the rate of the rxn?
The rate of the rxn will be halved.
Catalyst
biological enzyme, speeds up rxn by lowering activation E.
A catalyst helps the system reach what quicker?
equilibrium
Catalysts don’t affect
dG, equilibrium [reactants] or [products].
Catalysts are also called
enzymes
Catalysts provide favorable cond’s for a
rxn
Rxn Mech
explains making and breaking of bonds at molecular level.
Rxn Arrows
indicate direction of rxn (e- flow); e- pushing.
Isomerase
makes isomers.
Isomerase: a ketone to an aldehyde is an important part of?
glycolysis
H-bonding is a weak force compared to?
a covalent bond.
H-bonding forms the basis of?
double-helix in vivo.
Water’s polarity influences the strength of?
ionic interactions.
The polarity of a solvent is characterized by the?
dielectric constant (no units), reflects polarity.
Higher dielectric constant means?
more polar.
High dielectric constant of water means it can?
readily solubilize many ionic solids, can significantly decrease ionic interactions.
Something hydrophobic would have a low?
dielectric constant.
Polarity of water enables it to have?
ionic interactions.
In order to dissolve a fatty acid in water you would need to?
use organic / hydrophobic solvent to solubilize something w/ low dielectric constant.
Something with a low dielectric constant can’t?
form ions easily in water.
pKa
measures acid strength
Ka
acid ionization constant
Ka measures
acidity of a proton, how easily acid dissociates.
Ka =
[H+] [A−]/[HA]
pKa =
−log Ka
Ka for strong acids
high values bc fully dissociate in water.
pKa is involved in the interconversion of?
weak acids / weak bases.
When the pKa is high
it is less acidic, more basic, proton dissociates less easily.
In order to dissociate when the pKa is high you need to ass a lot of?
base.
When the pKa is low?
it is less basic, more acidic.
When the pH is low?
more (+), more likely to be protonated, more acidic.
When the pH is high?
more (-), less likely to be protonated, more basic.
when you add a proton to [A-] it becomes?
[HA]
pH measures?
acidity
Acidic pH levels?
0-6
Basic pH levels?
8-14
Neutral pH?
7
Buffers help maintain a?
neutral pH.
How do you determine [proton]?
log
Buffers
chemical systems resistant to changes in pH.
Buffers are mixtures of?
weak acids and conj. bases or weak bases and conj. acids.
Enzymes have optimum?
pH’s.
Buffering Capacity
relative amount of an acid / base that can be added to a volume of buffer soln before its pH changes.
The ideal pH that a particular weak acid or conj. base system will buffer is its?
buffering capacity.
the ideal pH is closest to a buffering agent’s?
pKa.
Buffer for copying DNA
add nucleotides (substrates for rxn), these have charges.
need correct complimentary buffer for acid / base you’re using.
weak acid / base in excess to buffer.
pH absolute # / [molecules] you have.
Henderson-Hasselbalch Equation calculates the?
pH of a buffer system.
pH = pKa + log [A-]/[HA]
Henderson-Hasselbalch Equation
Large [A-]/[HA] means?
more base, pH higher.
[A-]
weak base
You typically have the same amount of weak acid and conj. base when the pH is close to the?
pKa
You want to have excess of buffering agents in moles / molecules in comparison to?
enzymes / substrates / products.
