L14A: OXPHOS- The Process & L14B: ATP-Synthase

Question 1

what “mobile” e- carriers does the respiratory chain contain

Answer 1

Ubiquinone & Cytochrome C

Question 2

OXPHOS complex I

Answer 2

NADH dehydrogenase

Question 3

what happens in step1/complex1 OXPHOS

Answer 3

• transfers 4 e-s from NADH to ubiquinone
• so NADH -> NAD+ and Q -> QH2
• 4 protons pumped across matrix into intermembrane space

Question 4

complex 2

Answer 4

succinte dehydrogenase

Question 5

what happens in step/complex 2

Answer 5

• succinate dehydrogenase transfers e-s from succinate to FADH2 to ubiquinone
• so the e-s pass from succinate to FAD to FADH2 to FAD+ and Q to QH2

Question 6

complex 3

Answer 6

ubiquinone cytochrome-C oxidoreductase

Question 7

what happens step/complex 3

Answer 7

• end result is UQH2 transfers 2e-s to 2x 1CytC
• e- transfer drives expulsion of 4 more protons from matrix into intermembrane space

Question 8

complex 4

Answer 8

cytochrome oxidase

Question 9

complex/step 4

Answer 9

• transfers e-s from Cyt C to O2 (complete e- transfer)
• e-s transferred from Cyt C -> Cyt a -> Cyt a3 -> O2
• 4e- reduction of O2 -> H2O
• 2 protons transferred from matrix -> intermembrane space

Question 10

what inhibitor blocks e- transport between Complex 1 and Q

Answer 10

rotenone

Question 11

what inhibitor blocks e- transport between Complex 3 & 4

Answer 11

antimycin

Question 12

what inhibitor blocks e- transport between Complex 4 & O2

Answer 12

cyanide

Question 13

each NADH that donates e-s drives expulsion of how much H+

Answer 13

• 4H+ through Complex 1 & 3
• 2H+ through complex 4
  = 10 H+ to intermembrane space

Question 14

each FADH2 that donates e-s drives expulsion of how much H+

Answer 14

• 4H+ through complex 3
• 2H+ through complex 3
  = 6H+ travel to intermembrane space

Question 15

what creates PMF (proton motive force)

Answer 15

e- transfer

Question 16

what do inhibitors of e- transport do to ATP synthesis

Answer 16

block ATP synthesis

Question 17

what do inhibitors of ATP synthesis do to e- transfer

Answer 17

block e- transfer

Question 18

what are the 2 domains of ATP synthase

Answer 18

F1 and F0

Question 19

what kind of membrane protein is F1

Answer 19

peripheral membrane protein

Question 20

function of F1

Answer 20

catalytic domain - synthesises ATP

Question 21

what kind of membrane protein is Fo

Answer 21

integral membrane protein

Question 22

fucntion of F0

Answer 22

• proton pore
• H+ move through it against conc gradient from intermembrane space through F1 to matrix
• this proton flow enables ATP synthesis

Question 23

how many subunits in F1

Answer 23

9 subunits

Question 24

how many subunits in F0

Answer 24

3 subunits

Question 25

how does ATP synthase carry out function

Answer 25

* protons pass through F0 and cause cylinder of C units attached to gamma subunit of F1 to rotate * rotational catalysis causes ATP synthesis