2 - Energy in cell biology 2: magnitudes of energy in cells Flashcards
change in free energy determines
is a process occur spontaneously
In isolated system, ∆H =
0
entropy increase, ∆S
> 0
S=entropy=disorder
spontabeous process, ∆G
<0
what is used if available free energy ant reduce NAD+
it takes a lot of energy to reduce NAD+, it the free energy cant, they use FAD
ATP ∆G
-7.3kcal/mol
thermal energy
energy represented by random kinetic energy of water molecules in cytoplasm
-water molecules = always in motion
-their kinetic energy & random movement = HEAT
Thermal energy can serve as
baseline for cellular energy scales
KbT = (At baseline)
0.6 kcal/mol
Baseline: average amount of energy a particle has
Below 0.6 = indistinguishable
Boltzmann formula:
average aount of energy in particle
<E> = 3/2 KB x T
</E>
value for ATP hydrolysis =
~20 KBT
continusous motion of a particle due to random thermal energy
Brownian motion
molecules diffuse with a characteristic…
diffusion coefficient (D)
smaller molecule = … diffusion & … D
faster diffusion
larger D
Brownian motion = random
walk (1D-50% right/50% left)
Explores many spaces, but gets nowhere – goes back where they started
mean squared displacement <x^2>
<x^2> = 2 D t
diffusion coefficient - describes…
how fast a molecule is spread out
energies that compare with thermal energy (3)
Chemical energy
Mechanical energy (Work)
Electromagnetic energy
Cells and subcellular structures both
feel & produce mechanical forces
-push against plasma membrane to extend it
magnitude of cellular forces
measured in pN to nN
1 KBT = 4.1 pN/nm
1 photon =
= more energy than ATP
- which is why we can harness them to generate ATP
if complementary protein withpositively cahrged surface against a negatively charged surface, how much energy does it take to pull them together or apart. which eqaution do we use?
Coulombs law
-moving 2 opposites charges from 0.3nm -0.15nm apart (E = 2.3 KBT)
-thermal energy is not enough alone
-electrostatic repulsion is larger than thermal energy
Non-covalent bond & electrostatic bonds are broken by …
(which equation)
~1 in 20 collisions that has enough energy to break the bond
(~1011 collisions/s) - doesn’t last very long
Boltzman equation:
-probability that thermal energy reaches a level E
-probability of that a particular collision between 2 proteins solution will have a certain energy
How strong is a covalent bond?
E ~ 100 KBT
Collision breaks covalent bond every ~1024 years
ATP hydrolysis = … bank note
ATP hydrolysis = 20$ bank note (big enough to do something and small enough to avoid too much waste) (E ~ 20 KBT)
