LECTURE 14 - ETC AND OXPHOS: A CLOSER LOOK

Question 1

how are the three negative charges of phosphate neutralised in vivo?

Answer 1

In vivo the molecule is H2PO4 that is transporting the H+, that is how the three charges are canceled out to be electroneutral

Question 2

how does the ATP/ADP carrier and what facilitates movement?

Answer 2

When ATP is made by ATP synthase, the ATP is exported out of the mitochondria so that the cell can use it → ADP comes in, cotransporter
ATP on the IMS has 4 negative charges, because it is + in the intermembrane space, facilitates the ATP going out
ADP goes in towards the more negative matrix because it only has 3 negative charges so is ‘more positive’ and flows in

Question 3

how do the charges of the ATP/ADP carrier work out?

Answer 3

Further hyperpolarizes the membrane, but phosphate carrier coming in makes it electroneutral
So, combining the ADP/ATP carrier and the phosphate carrier makes everything electroneutral even though the electrochemical gradient facilitates ATP moving out towards the positive outside

Question 4

why do we not consider the pH change since more hydrogens are brought in?

Answer 4

pH gradient is negligible in comparison to the electro- part of the electrochemical gradient

Question 5

what is adenine nucleoside translocase?

Answer 5

F0 subunit of the ATP synthase is in the membrane
Has 8 C subunits
Proton goes through each subunit
Each time a proton goes through, the synthase rotates overall 360 degrees
3 ATP made

Question 6

what is the mechanism of the adenine nucleoside translocase?

Answer 6

1. Empty C state
   ‘Cup’ is open to the intermembrane space
2. ADP binds, there’s a conformational change
3. Opens up, ADP is released to the matrix
4. Empty M state
   Cup is open to matrix
5. ATP binds, conformational change
   Opens up, ATP is released to intermembrane space

Question 7

why did UCP1 evolve from?

Answer 7

evolved from adenine nucleoside translocase

Question 8

why is UCP1 inhibited by ATP?

Answer 8

Don’t want it to be constitutive because it generates heat

Question 9

what is the nernst equation?

Answer 9

deltaG=-n(F)(deltaE)
n=number of electrons
F= faraday’s constant (96.4kJ/V/mol)
E=acceptor-donor

Question 10

why are only 3 ATPs made per every turn?

Answer 10

there are 3 alpha and 3 beta subunits in the F1 component of ATP synthase
ADP bind between the subunits, so there are only 3 spots where ADP can bind