Oxidative Phosphorylation

Question 1

What are the cofactors produced in the TCA cycle that are harvested for their high-energy electrons

Answer 1

NADH and FADH2

Question 2

Which direction is the proton concentration gradient in the mitochondria

Answer 2

High in the intermembrane space and low in the matrix

Question 3

Where does the energy come from which drives ATP synthase

Answer 3

Proton flow across the membrane

Question 4

What is the benefit of having many steps in the electron transport chain

Answer 4

no large amounts of energy are produced at one time so no energy is wasted or lost

Question 5

which direction in redox potential do electrons flow

Answer 5

from negative to more positive (thermodynamically favoured)

Question 6

what are the benefits of the invaginations of the mitochondrial inner membrane

Answer 6

increase the surface area - more comlexes
allow the creation a proton imbalance

Question 7

what are the two stages of oxidative phosphorylation

Answer 7

electron transport from NADH and FADH2 to O2 via the respiratory chain
ATP synthesis from the energy stored in the electrochemical gradient of protons

Question 8

is ATP synthesis related to electron movement or proton movement

Answer 8

protons

Question 9

when electrons flow along the respiratory chain what does this transfer of energy cause

Answer 9

conformational changes allowing the flow of protons across the membrane

Question 10

what are the names of the four complexes of the respiratory chain

Answer 10

complex I - NADH-Q-reductase (Q = ubiquinone)
complex II - succinate dehydrogenase
complex III - cytochrome c reductase
complex IV - cytochrome c oxidase

Question 11

what are the names of the two non-complex aspects of the respiratory chain

Answer 11

ubiquinone
cytochrome c

Question 12

at which complexes do NADH and FADH2 enter the respiratory chain

Answer 12

NADH at complex I
FADH2 at complex II (because it has less energy)

Question 13

which complex of the respiratory chain does not pump protons across the inner mitochondrial membrane

Answer 13

complex II (succinate dehydrogenase)

Question 14

complex I and II both reduce what

Answer 14

ubiquinone

Question 15

what does complex III reduce

Answer 15

cytochrome c

Question 16

cytochrome c is oxidised by what

Answer 16

cytochrome c oxidase

Question 17

which complex of the respiratory chain produces water by donating electrons to oxygen

Answer 17

cytochrome c oxidase (complex IV)

Question 18

what is the only channel through which protons can move down they’re electrochemical gradient across the inner mitochondrial membrane

Answer 18

ATP synthase

Question 19

which side of the inner mitochondrial membrane do protons ‘want’ to be on

Answer 19

matrix side

Question 20

which is a stronger driving force for the flow of protons, charge or concentration (pH)

Answer 20

charge

Question 21

where is each subunit of ATP synthase located

Answer 21

F1 - protruding into the mitochondrial matrix
F0 - in the inner mitochondrial membrane

Question 22

what causes the F1 subunit of ATP synthase to rotate

Answer 22

the flow of protons through the F0 region proton channel

Question 23

what does the rotation of the F1 subunit of ATP synthase cause

Answer 23

a conformational change and contraction which brings ADP and Pi close together producing ATP

Question 24

what is the terminal electron acceptor in the respiratory chain
what does it produce

Answer 24

oxygen
water

Question 25

what is the P/O ratio measurement of

Answer 25

the number of inorganic phosphates (P) incorporated into ATP per atom of oxygen (O) reduced

Question 26

what is the P/O ratio if NADH is oxidised to NAD+

Answer 26

2.5

Question 27

what is the P/O ratio if FADH2 is oxidised to FAD

Answer 27

1.5

Question 28

What are the final yields of glycolysis and the TCA cycle (ATP, NADH + H+, FADH2)

Answer 28

Glycolysis: 2 ATP, 2 NADH + H+
Pyruvate dehydrogenase: 2 NADH + H+
TCA cycle: 6 NADH + H+, 2 FADH2, 2 ATP

Total: 4 ATP, 10 NADH + H+, 2 FADH2

Question 29

What are the cofactors produced in the TCA cycle that are harvested for their high-energy electrons?

Answer 29

NADH and FADH2