biophysics

Question 1

water characteristics

Answer 1

dipolar (H-bonding) > high bp
hydration cell of interactions

Question 2

solubility of larger biological molecules

Answer 2

more polar / charged side groups = higher solubility

Question 3

charged side groups

Answer 3

amino
carboxyl
phosphate

Question 4

polar side groups

Answer 4

alcohol
thiol
carbonyl
ester
amide

Question 5

hydrophibicity

Answer 5

apolar groups disrupt H-bonding
drives protein folding

Question 6

ampiphatic

Answer 6

both polar and non-polar end

Question 7

brownian motion

Answer 7

thermal energy moving molecules in solution

Question 8

diffusion

Answer 8

net flux of molecules down a concentration gradient due to random thermal motion

Question 9

what drives passive transport across membranes

Answer 9

steady state diffusion

Question 10

flux equation

Answer 10

J = P (C1-C2)
J= flux
P= permeability

Question 11

time scale to transverse distance R with diffusion coefficient D

Answer 11

T=R^2/6D

Question 12

U/ internal energy

Answer 12

capacity of a system to do work

Question 13

chemical potential

Answer 13

determined by:
chemical bonds within
intermolecular bonding

Question 14

1st law of thermodynamics

Answer 14

change in H = change in U + p (change in V)
enthalpy change = energy released by a reaction - work

Question 15

ammonium nitrate solution

Answer 15

favourable but has positive enthalpy change

Question 16

entropy

Answer 16

measure of system disorder

Question 17

2nd law of thermodynamics

Answer 17

entropy of an isolated system will either increase or remain the same

Question 18

entropy vs enthalpy

Answer 18

large change in entropy can drive a reaction despite enthalpic favourability

Question 19

positive change in enthalpy

Answer 19

order to disorder

Question 20

high to low enthalpy

Answer 20

negative change in enthalpy of system

Question 21

Boltzmann formula

Answer 21

entropy = boltzmann constant *ln(number of accessible microstates)

Question 22

Boltzmann constant

Answer 22

1.3*10^-23 J/K

Question 23

minimum entropy

Answer 23

0

Question 24

entropy relation to microstates

Answer 24

less entropy = less translational microstates accessible

Question 25

KE relation to accessible microstates

Answer 25

as KE decreases so does number of accessible microstates

Question 26

entropies of perfectly crystalline substances at 0K

Answer 26

0

Question 27

Gibbs free energy function

Answer 27

determines whether reaction is favourable

Question 28

Gibbs free energy equation

Answer 28

free energy change = enthalpy change - temperature*entropy change

Question 29

Gibbs free energy change at constant temp and pressure

Answer 29

- temperature * change in total entropy

Question 30

when is a reaction feasible?

Answer 30

when free energy change is negative

Question 31

when is a reaction not feasible?

Answer 31

when free energy change is positive?

Question 32

G in relation to useful work

Answer 32

what's left from internal energy and entropy changes in system after taking away wasted work

Question 33

ATP synthesis favourability

Answer 33

unfavourable as gibbs energy change is + couple to H+ transport

Question 34

when do molecules react in a collision

Answer 34

if KE > Ea

Question 35

what does most probable speed depend on?

Answer 35

mass/ temp

Question 36

kinetic energy formula

Answer 36

1/2 m v^2

Question 37

Kinetic energy average formula

Answer 37

3/2KbT

Question 38

what does RoR depend on?

Answer 38

temp enzymatic catalysis concentration

Question 39

first order reactions

Answer 39

single atom or molecule determines rate e.g decomposition

Question 40

rate of decomposition

Answer 40

k[A]

Question 41

2nd order reactions

Answer 41

when 2 molecules collide to determine rate

Question 42

rate of 2nd order reactions

Answer 42

k[A]^2

Question 43

rate of bimolecular reaction

Answer 43

k[A][B]

Question 44

how are orders of reaction found?

Answer 44

experimentally or by full knowledge of the kinetic pathway

Question 45

what's order of a reaction controlled by?

Answer 45

the slowest, rate-limiting step of a reaction

Question 46

Kc

Answer 46

[AB]/[A][B]

Question 47

Kc effect on product yield

Answer 47

Kc >> 1 (mostly product) Kc << 1 (mostly reactant) Kc = 1 (mixture)

Question 48

Le Chatelier's principle

Answer 48

"when a system at eq is disturbed, system composition adjusts to minimise the disturbance"

Question 49

equilibrium formula for gibbs free energy change

Answer 49

-RTlnKeq R= gas constant

Question 50

exponential effect on equilibrium constant

Answer 50

makes v sensitive to small changes in gibbs free energy

Question 51

pH formula

Answer 51

-log10[H+]

Question 52

pH effects

Answer 52

affects protein solvation enzyme activity

Question 53

pH effect on cells

Answer 53

6-7 death 7-7.35 acidosis 7.45-7.8 alkalosis 7.8-9 death

Question 54

2H2O dissociation

Answer 54

H3O+ + OH- hydroxonium doesn't exist in water

Question 55

equilibrium constant of water

Answer 55

([H+][OH-])/[H2O]^2 H2O doesn't change in aq solutions so Kw = [H+][OH-]

Question 56

Kw at 25 degrees celcius

Answer 56

1*10^-14 therefore [H+]=[OH-]=1*10^-7

Question 57

free energy

Answer 57

weighted sum of partial molar Gibb's energy

Question 58

entropic effect of mixing A with other components

Answer 58

RTln[A]

Question 59

conc difference enthalpy balancing reverse

Answer 59

electrical potential difference

Question 60

Nernst potential

Answer 60

electrical potential difference required to stop flow of ions arising from conc difference

Question 61

change in potential energy

Answer 61

q*change in v

Question 62

chemical potential difference

Answer 62

zFchange inV

Question 63

F

Answer 63

Faraday's constant

Question 64

impermeable macromolecule charge density

Answer 64

125mM conc of e-=

Question 65

Donnan equilibrium

Answer 65

equilibrium internal concentration of each ion and membrane potential difference

Question 66

sodium anomaly

Answer 66

Nernst potential of Na is far more + than membrane potential cellular osmolytes required so cell doesn't burst

Question 67

how does pH imbalance store free energy

Answer 67

chemical contribution (concentration gradient) electrostatic contribution (potential difference)

Question 68

combination of chemical and electrostatic contribution

Answer 68

proton motive force -200mV

Question 69

rotary motors powered by proton flux

Answer 69

ATP synthase and bacterial flagellar motor