Lecture 25/26: Oxidative Phosphorylation & Regulation

Question 1

In OxPhos, electrons are transferred from what to what

Answer 1

NADH and FADH2 –> O2

Question 2

Oxidative phosphorylation occurs where

Answer 2

Inner membrane of mitochondira

Question 3

Which of the complexes in the ETC does not pump protons

Answer 3

Succinate Q reductase (Complex II)

Question 4

FADH2 enters ETC where and its electrons are transferred where

Answer 4

FADH2 enters through succinate-q reductase (Complex II)
It does not leave the complex
Its electrons are transferred to Coenzyme Q

Question 5

Which complexes make up the respirasome

Answer 5

Complexes I, III, IV

Question 6

Coenzyme Q AKA ubiquinone function

Answer 6

Transfers electrons from complexes I and II to complex III

Question 7

Cytochrome C function

Answer 7

Shuttles electrons from Complex III to Complex IV
Final component of the ETC
Catalyzes reduction of O2

Question 8

Iron sulfur clusters

Answer 8

Play role in reduction reactions

Undergo oxidation-reduction reactions but the protons never leave the protein

Question 9

Complex I

Answer 9

NADH-q oxidoreductase or NADH dehydrogenase
First point of entry of electrons from NADH
Protons are pumped to cytoplasmic side

Question 10

Complex II

Answer 10

Succinate-q reductase
FADH2 enters ETC here
Does not pump protons, therefor less ATP is produced from oxidation of FADH2

Question 11

Complex III

Answer 11

Cytochrome C oxidoreductase
Electrons from QH2 (reduced coenzyme Q) are passed on to cytochrome C by this complex
2 Protons are pumped to cytoplasmic side

Question 12

Complex IV

Answer 12

Cytochrome C oxidase
Transfers 4 electrons from reduced Cytochrome C to O2
Protons are pumped to cytoplasmic side

Question 13

Cytosolic superoxide dismutase vs mitochondrial

Answer 13

Cytosolic- Cu/Zn

Mitochondrial- Mn/Zn

Question 14

ATP synthase uses energy derived from what to drive phosphorylation of ATP

Answer 14

Proton motive force

Question 15

Is the inner mitochondrial membrane permeable to H+ and OH ions?

Answer 15

No, if the membrane was permeable, a proton motive force would not be able to be established

Question 16

Complex V contains F0 and F1 subunits that each have subunits of their own. Which subunit of F1 is catalytically active

Answer 16

only Beta subunits

Question 17

What allow the proton gradient to be in close proximity to ATP synthase

Answer 17

The cristae

Question 18

What is complex 6

Answer 18

ATP-ADP translocase family, reside in inner and outer mito-membranes
Flow of ATP/ADP coupled - one in and one out

Question 19

Malate aspartate shuttle operates in what organs, generates what, and where does it enter the ETC

Answer 19

Operates in the heart, liver and kidneys

Generates NADH which enters ETC at Complex I

Question 20

Glycerophosphate shuttle operates where, generates what, and where does it enter the ETC

Answer 20

Skeletal muscle and brain

Generates FADH2 which enters ETC at CoQ

Question 21

What happens when transfer of electrons is inhibited

Answer 21

Decrease in proton pumping
Decrease in protein gradient
Inhibition of ATP synthesis

Question 22

What is thermogenin AKA UCP-1

Answer 22

Uncoupling protein that uncouples oxphos from ATP synthesis. This is done in brown adipose tissue and is used to generate heat instead of ATP
-Transfers protons from cytoplasmic side to matrix to generate heat

Question 23

Malonate

Answer 23

Inhibits complex II

Question 24

What toxins inhibit complex IV

Answer 24

CO
Cyanide
H2S

Question 25

Oligomycin

Answer 25

Inhibits complex V

Question 26

Antimycin

Answer 26

Inhibits complex III

Question 27

What toxins inhibit complex I

Answer 27

Amytal
Myxothiazol
Rotenone
Piericidin A

Question 28

What two factors constitute the proton motive force

Answer 28

pH gradient

Membrane potential

Question 29

ATP synthase molecules associate with each other to form ____ which come together to form ____

Answer 29

Dimers come together to form oligomers