Oxidative Phosphorylation

Question 1

Where does Ox Phos occur?

Answer 1

In the inner membrane of mitochondria

Question 2

Where does TCA and fatty acid oxidation occur?

Answer 2

In the matrix of the mitochondria

Question 3

What three components make up successful Ox Phos?

Answer 3

1. transfer electrons from NADH and FADH2 to O2
2. Establish proton gradient across inner membrane mitochondria
3. Synthesize ATP

Question 4

What complexes pass electrons from NADH to O2?

Answer 4

NADH Q oxidoreductase (complex I)
Q cytochrom c oxidoreductase Complex III
Cytochrome C oxidase Complex IV
Called the Respirasome
Flow of E- across inner membrane

Question 5

What are the mobile electron carriers?

Answer 5

Coenzyme Q aka Ubiquinone which transfers electrons from C1 to CII to CIII

Cytochrome C which shuffles electrons from Q cytochrome C oxidored. (CIII) to Cytochrome C oxidase (CIV)

Question 6

What is another name for complex one?

Answer 6

NADH Dehydrogenase or NADH-Q Oxidoreductase

First point of entry and both nuclear and mito genes

Question 7

What is another name for complex two and what enters ETC through it?

Answer 7

Succinate-Q reductase and FADH2 enters it connects krebbs to oxphos. DOESN’T pump protons so less ATP from ox of FADH2

Question 8

What is another name for complex III?

Answer 8

Cytochorme C oxidoreductase where electeons from QH2 are passes to cytochrome c. Moves 2 protons to the cytoplasmic side

Question 9

What is another name for complex four?

Answer 9

Cytochrome C Oxidase. transfers electrons from reduced Cyt. C to molecular oxygen

Question 10

What is the final electron carrier?

Answer 10

oxygen

Question 11

What are examples of ROS?

Answer 11

Superoxide ion, peroxide ion, and hydroxyl radical from the partial reducction of oxygen

Question 12

Five Antioxidants?

Answer 12

SOD
Catalase
Glutathione peroxidase
Vit. E
Vit. C

Question 13

Describe the flow of electrons in the gradient?

Answer 13

Flows from molecules with lower Eo’ highest Eo’

Question 14

What leads to the pumping of H ions from matrix to IMS?

Answer 14

Electron transfer through respiratory chain

Question 15

What two factors make up the Proton motive force to drive ATP synthesis by Complex V?

Answer 15

pH gradient and membrane potential

Question 16

What are the three postulates of the chemiosmotic theory?

Answer 16

1. ETC translocates protons across IMS across the complexes
2. ATP synthase uses proton motive force to drive phosphorylation of ADP
3. Inner membrane is impermeable to H and OH ions, if cant be disrupted a pmf cant be established and ATP synthesis doesn’t occur

Question 17

What is another name for complex V?

Answer 17

ATP Synthase

Question 18

Describe structure of ATP synthase?

Answer 18

Ball and Stick structure
Fo subunit is stick embedded in the membrane with a proton channel anad the F1 subunit is a ball that protrudes into matrix side and contains catalytic domains

Question 19

How are the alpha and beta F1 subunits arranged?

Answer 19

alternately in a hexameric ring both bind nucleotides but only the beta are catalytically active

Question 20

What allows the proton gradient to be in close proximity to ATP synthase?

Answer 20

The Cristae

Question 21

What disrupts proton transport through the channel in ATP synthesis?

Answer 21

Oligomycin

Question 22

Are ATP/ADP permeable across mitochondrial membrabe?

Answer 22

No they need a carrier, an ATP-ADP translocase family which resides in the outer and inner mito membranes and works with mito carriers

Question 23

How does ATP and ADP flow into and out of matrix?

Answer 23

ADP enters matrix only if ATP leaves it. Known as complex 6

Question 24

What are the two shuttle systems for reduced NADH to cross mito. membrane?

Answer 24

Malate aspartate shuttle and Glycerophosphate shuttle

Question 25

Where is the malate aspartate shuttle found?

Answer 25

Heart liver and kidneys and it generates NADH in mitochondrial matrix and NADH enters ETC at complex I

Question 26

Where is the glycerophosphate shuttle found?

Answer 26

Skeletal muscle and brain. It generates FADH2 in the inner mitochondrial membrane FADH2 joins ETC at CoQ

Question 27

How do levels of ATP regulate respiration?

Answer 27

Electrons only flow through the ETC when ADP is phosphorylated to ATP.

Question 28

What is regulation by ADP called?

Answer 28

Respiratory control or acceptor control

Question 29

What happens if Oxphos is inhibited?

Answer 29

Decrease in pumping of protons and a decrease in the protein gradient and inhibition of ATP synthesis because there is no PMF

Question 30

In hibernating animals where does the uncoupling of oxphohs from ATP synthesis to generate heat occur?

Answer 30

in brown adipose tissue

Question 31

How does uncoupilng and heat generation occur?

Answer 31

Inner mito membrane contains uncoupling protein UCP1 aka thermogenin which transfers protons from IMS to matrix. Energy converted to heat instead of ATP. UCP 2 and 3 also uncouple oxphos from ATP synthesis.