5 Bioenergetics - Lecture Flashcards
Potential Energy
objects not in motion but have capacity to do work
Kinetic Energy
energy of motion (ex. ions rushing into cell)
Thermodynamics
study of energy transfer what goes in = what comes out
1st Law of Thermodynamics
Energy can be neither created nor destroyed. It can only be converted from one form to another.
Examples diff forms of energy can be inter-converted:
1)PE due to position to KE to Heat E 2)Chemical Bond E in water and O2 to rapid molecular motions in water to heat E
ΔE
-The change in internal energy of a biological system -E transformations consider the system & environment -relates to heat & work -NOTHING to do with spontaneity - ΔE = Q-W Q = heat energy W = work energy
2nd Law of Thermodynamics
-energy transformations occur spontaneously so that matter is transformed to a more random state -Reversal of tendency towards entropy requires energy
Gibb’s Free Energy
-the E available to do work ΔG = ΔH - TΔS ΔG=change in available E ΔH= change in enthalpy TΔS=unavailable E (lost as entropy) potential factor: T in Kelvin or DegC + 273 capacity factor: entropy (ΔS calories (E)/degrees)
Exergonic reactions:
-Products contain less energy than reactants –energy is released. -They are spontaneous because they require no input of energy (Note: This does not mean “fast.”
Spontaneous
Releases Free Energy ( -ΔG)
Products have less energy than reactants
Endergonic reactions:
-Products contain more energy than reactants. -Non-spontaneous - require an input of energy.
Not Spontaneous
Must consume Gibbs Free Energy (+ΔG)
Products have more energy than reactants
+ΔG
-ΔG
ΔG=0
spontaneous (exergonic)
non-spontaneous (endergonic)
at equilibrium
Are chemical rxns in cell reversible?
YES
What is the:
dissociation rate? Koff
association rate? Kon
At equilibrium: the association rate ____ dissociation rate
formula?
=
Keq = [AB] / [A] [B]
(Kon/Koff)
Free energy changes in chemical reactions at standard conditions…explain:
What is standard free E equation?
ΔGo’ = - RTlnKeq or
ΔGo’ = - 2.303 RTlogKeq
ΔGo’ = standard free energy at standard conditions, where T=25C (298K), 1 atm pressure, all reactants and products are at 1 M concentration, except for water is present at 55.6 M, and pH = 7.0.
Free energy changes under non-standard conditions:
(reality in cell)
ΔG = ΔGo’ + RT ln [products]/[reactants]
or
ΔG = ΔGo’ + 2.3(RT) log [products]/[reactants]
The free energy of any cellular reaction is a function of the nature of the reaction itself (DGo’) as well as the initial concentrations of the reactants and products.
What is bioenergetics?
the study of the flow and transformation of energy in and between living organisms and between living organisms and their environment
Types of Energy used or produced by cells: (6)
- Chemical energy
- Mechanical energy
- Heat or thermal energy
- Sound
- Electrical energy
- Light or electromagnetic energy
Living cells produce exquisitely ordered structures with a high or low entropy?
low entropy (disorder)
How do cells maintain increased order?
a system (i.e. the cells) can sustain an increased order if the entropy in the surroundings (i.e. outside the cell) increases. The end result is that the entropy in the universe increases.
In biological systems, heat lost to the environment, increases the random movement of molecules in its surroundings to increase disorder.
obey 2nd law of thermodynamics
Energy Cycle (pic)
Describe free energy & entropy in:
anabolic rxns
catabolic rxns
anabolic:
free E inc. entropy dec.
catabolic:
free E dec. entropy inc.
photosynthesis:
metabolism:
is the sum of all anabolic and catabolic reactions in a cell or organism.
Anabolism;Condensation polymerization;Deyhydration synthesis;endergonic
Catabolism;Hydrolysis;exergonic
Mammalian cells metabolize _____ to produce ____ (hypoxic conditions) or ___ (anoxic conditions)
carbohydrates ATP NAD+
Glycolysis?? double check in book
Mitochondria completes the ___ of ___ by converting ___ to ____
oxidation carbohydrates pyruvate stored energy (ATP)
ATP synthase generates __ inside the ___
ATP mitochondria
ATP synthase in the inner mitochondrial membrane drives the synthesis of ATP using the ___________
Where is [H+] gradient high in? low in? What is stored as?
[H+] gradient (potential energy)
The elecrochemical [H+] gradient (high in inner membrane space/low in mitochondria matrix) is stored potential energy
ATP: energy is stored in __ high-energy ___ bonds
2 phosphate
ATP hydrolysis is highly energetically ______
ATP =
favorable (exergonic)
ADP + Pi
favored rxn?
equilibrium?
disfavored rxn?
ΔG < 0 favored reaction (Spontaneous)
ΔG = 0 neither the forward nor the reverse reaction prevails (Equilibrium)
ΔG > 0 disfavored reaction (Nonspontaneous)
What drives most of the endergonic reactions that occur in a cell?
ATP
Reaction coupling allows energetically-___ reactions (+ΔG) to be driven by ___ ones (-ΔG) (unfav or fav?)
Reaction coupling with ___ reactions drives most ____ reactions in the cell (endo exo?)
unfavorable favorable
exergonic endergonic
The Metabolism of Living Cells Maintains ___ Intracellular ATP Concentration (low or high?)
Cells maintain a steady state (where reactants and products remain relatively constant) having a ___ [ATP].
Is [ATP]/[ADP] is at equilibrium? At equilibrium, there’s more:
cells must have stored E to live
High
high
Never ADP
