bioenergetics 1 and 2? Flashcards
anabolic reactions
- synthesis of complex molecules from simple ones
- energy-storing reactions
catabolic reactions
- degradation of complex molecules into simpler ones
- energy is released
metabolism
total chemical reactions
1st law of thermodynamics
energy is neither created nor destroyed - only transformed
what are the different types of energy?
- kinetic
- potential (gravitational and elastic)
- thermal (heat)
- chemical
- electrical
- light
- nuclear
- mechanical
why does energy eventually lose the ability to do useful work?
due to degradation of energy:
as energy undergoes multiple transformations, it becomes increasingly dispersed and less concentrated in forms that can be harnessed to do useful work
- “quality” changes
- The energy is ‘diluted’
- Energy can lose its ability to ‘do’ work
what is Gibbs free energy?
energy that can be harvested by an organism
Gibbs free energy equation?
enthalpy = free energy + (absolute temperature x entropy)
or
H = G + (TxS)
heterolytic fission
pair of electrons is taken by one of the atom
homolytic fission
he pair of electrons is split between the separated atoms
nucleophile
electron rich
- negatively charged or have unshared electron pair
- easily form covalent bonds with electron deficient centers
electrophile
electron-deficient
- positively charged, contain an unfilled valence electron shell or contain a electronegative atom - form covalent bonds with electron rich centers
electrophile examples
protons
metal ions
carbonyl carbon atoms
cationic immune
nucleophile examples
hydroxyl groups
sulfhydryl group
amino group
imidazole group
group transfer reactions
nvolve the transfer of an electrophilic group from one nucleophile to another –> nucleophilic substitution
oxidation reaction
reduction reaction
redox reaction
isomerisation
involve the intra molecular shift of a hydrogen to change the location of a double bond
rearrangement
produce altered carbon skeletons
Gibbs free energy equation
ΔG = ΔH - ( T x ΔS)
Gibbs free energy = change in enthalpy - ( temperature x change in entropy)
decarboxylation
Reaction are often followed by electron/bond rearrangement to find the most stable form
what does ΔG < 0 indicate?
- value is negative
- process is spontaneous
- dec in Gibbs energy accompanied by inc in entropy which doves reaction forwards
what does ΔG = 0 indicate?
- the system is at equilibrium
- occurs at a constant rate in both directions
what does ΔG > indicate?
- value is positive
- the process is not spontaneous
in a spontaneous process, a system:
- gives up energy ( so dec in H)
and/or - becomes more random (inc in S)
1st law of thermodynamics
energy is neither created nor destroyed, only transformed
2nd law of thermodynamics
all energy transformations ultimately increase the entropy of the universe
how may a non-spontaneous reaction occur?
- if lined reaction is sufficiently exergonic ( releases a lot of free energy)
- i.e if ΔG1 + ΔG2 < 0
draw energy diagram for endergonic reactions
draw energy diagram for exergonic reactions
How would the addition of a catalyst to the reaction S⇋P affect the difference between the free energies of S and P in their ground states (∆G’°)?
∆G’° would not change
For the enzyme-catalyzed reaction E + S ⇋ ES ⇋ E + P, what equation defines the rate at which ES is formed?
k1([E_t] - [ES])[S]
How can the Michaelis-Menten constant, be derived from this Lineweaver-Burk plot?
The x-intercept is equal to -1/Km therefore Km= -1/(x-intercept)
the equation of a line is y = mx + b.
Michaelis-Menten equation states that
V0= (V_{max}[S])/(K_m + [S]
the inverse of this equals
(
.This equation is the simple y=mx + b equation that defines the line in the Lineweaver-Burk plot.
Hint #55 / 6
Because x = 1/[S], we can see that the slope of this line would be equal to
. Also notice that
is the inverse of the y-intercept.
If the enzyme-catalyzed reaction E + S ⇋ ES ⇋ E + P is proceeding at or near the V
of E, what can be deduced about the relative concentrations of S and ES?
S is abundant, and [ES] is at its highest point.
What relative values of Km and kcat would describe an enzyme with a high catalytic efficiency?
Choose 1 answer:
low Km and high Kcat
For the enzyme-catalyzed reaction E + S ⇋ ES ⇋ E + P, what is the value of K
if [S]=25, and the initial reaction velocity is half of V?
25
With respect to the binding of regulatory compounds, what properties define an enzyme as being allosteric?
reversible
non-covalent binding of regulatory compounds
