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Flashcards in bcm34 Deck (22):
1

simple chemiosmotic system

bacteriorhodopsin

2

3 neccessary components of chemiosmotic system

proton pump
two compartments
f type atpase

3

pmf equation

change in pmf (mV) = membrane potential (mV) -59 * change in ph

4

how many H+/atp

1 turn = 3 atp
1 c= 1 proton
octameric c rotor
= 8H+/3Atp
=2.7H+

5

how many c subunits?

8 in mammals
8-14 observed
14 is in plastids with 2H+/atp

6

why is H+ amount quoted sometimes as 4/3

as proton consumed by translocase bringing atp

7

how do we know proton gradient is neccessary

uncoupling agents prevent atp synthesis

8

give examples of uncoupling agents

salicyclic acid
valinomycin - transport K+ ions from inner membrane to matrix
dinitrophenol transports h+ through the membrane

9

brown fat in babies

deliberate uncoupling of lipid oxidation from atp synthesis
uncoupler = thermogenin = heat generator

10

arum lilies

uncouple mitochondira to generate inflorescences

11

titan arum

vapourise amines to attract flies via uncoupling to produce heat

12

skunk cabbage

symplocarpud foetidus
uncouples to melt snow

13

how are many chemiosmostic systems driven?

by redox

14

what is the standard reduction potential of a half reaction?

E^0
free energy of a reduction expressed in volts

15

how do you calculate voltage generated by 2 coupled half cells

change in e^o = E^0 red - E^0 ox

16

how are voltage differences related to free energy?

delta g = zf delta E
E = E^0 + RT/zF ln [x]ox/[x]red

17

what do electrons flow spontaneously from?

more negative redox potential to more positive

18

what is redox potential?

measure of tendency of chemical species to aquire electrons and be reduced measured in volts

19

what is chemiosmosis?

coupling of spontaneous flow of H+ down gradient to non spontaneous atp synthess

20

how does uncoupling produce heat?

energy from proton motive force is disspitated as heat

21

what do ab and delta subunits of atpase do?

they are stators
prevent head from rotating

22

describe the process of atp production

1. H+ enter rotor at c subunits
2. turning of f0 is coupled to rotation of lambda axis
3. causes a conformational change in alpha and beta of f1
4. beta = catalytic alternate between, open, tight, lose
5. open adp and pi bind
6. loose - adp phosphorylated to atp
7. atp protein stabilised tightly bound
8. energy rellease provided by motion of axle which pops freshly synthesized atp from active site converting back to open