regulation of oxidative phosphorylation

Question 1

a successful OxPhos must accomplish these goals:

1.

2.

3.

Answer 1

1. transfer electrons from NADH and FADH₂ → O₂
2. establish a proton gradient across the inner mitochondrial membrane
3. to synthesize ATP

Question 2

electrons flow from molecules

Answer 2

with lower E_o to those with highest E_o

Question 3

the difference in deltaE_o is associated with

Answer 3

deltaG^o

Question 4

deltaE_o and deltaG^o are _______ related

Answer 4

inversely

Question 5

deltaG^o =

Answer 5

-nFdeltaE_o

Question 6

chemiosmotic hypothesis

Answer 6

electron transfer through the respiratory chain leads to the pumping of H⁺ from matrix to the innermembrane space

Question 7

what 2 factors constitues a proton-motive force (pmf) to drive ATP synthesis by complex V

Answer 7

1. pH gradient (deltapH)
2. membrane potential

Question 8

3 postulates of chemiosmotic theory

Answer 8

1. the mitochondrial electron-transport chain translocates protons across the inner mitochondrial membrane as electrons flow from one respiratory electron-transport chain complex to the next
2. ATP synthase uses the proton motive force (pmf) to drive the phosphorylation of ADP
3. the inner mitochondrial membrane is impermeable to H⁺ and OH^- ions. if the membrane is disrupted, a pmf cannot be established, and ATP synthesis does not occurs

Question 9

ATP synthase (complex V) is located

Answer 9

embedded in inner membrane

Question 10

F_o subunit of ATP synthase

Answer 10

is stick-embedded in membrane

has a proton channel

Question 11

F₁ subunit of ATP synthase

Answer 11

is ball- protudes into matrix

contains catalytic domains

Question 12

F₁ subunits alpha and beta are arranged alternately in a hexameric ring, both bind nucleotides but only _______ are catalytically active

Answer 12

beta

Question 13

ATP synthase molecules associate with each other to form

Answer 13

dimer

Question 14

ATP synthase dimers come together to form

Answer 14

oligomers that stabilize the individual molecules to rotational forces requried for catalysis

Question 15

ATP synthase maintains _______ in inner membrane

Answer 15

curvature

Question 16

cristae allow

Answer 16

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

Question 17

1 mol of ATP requires

Answer 17

3 + 1 H⁺ passage [3 of which are being used in the F₀ turbine (cyclothorn) to move ADP to a closer proximity to the complex]

Question 18

oligomycin

Answer 18

disrupts proton transport through the channel

Question 19

ATP and ADP are _______ across the mitochondrial membrane

Answer 19

not permeable

Question 20

ATP-ADP translocase family

Answer 20

reside in the outer and innter mitochondrial membranes

works with mitochondrial carriers

Question 21

flow of ADP and ATP are coupled, ADP enters matrix

Answer 21

only if ATP leaves

Question 22

ATP-ADP translocase has recently been called

Answer 22

complex VI

Question 23

reduced NADH cannot cross the mitochondrial membrane, it requires these shuttle systems:

Answer 23

1. malate-aspartate shuttle
2. glycerophosphate shuttle

Question 24

malate-aspartate shuttle

Answer 24

NADH donates protons to malate which goes through outer and inner membrane shuttle and donates protons back to NADH to enter ETC

Question 25

glycerophosphate shuttle

Answer 25

NADH donates protons to glycerol 3-P which translocates across outer membrane through its shuttle and then donates its protons to complex II (FAD)

Question 26

malate-aspartate shuttle operates in what tissues

Answer 26

heart, liver, and kidneys

generates NADH in mitochondrial matrix

NADH enter into ETC at complex I

Question 27

glycerophosphate-shuttle operates in

Answer 27

skeletal muscle and grain

generate FADH₂ in the inner mitochondrial membrane

FADH₂ joins ETC at CoQ (which is very close to complex II)

Question 28

what inhibits the activity of PDH/PDC

Answer 28

high levels of acetyl CoA, NADH, and ATP

(high energy)

Question 29

what activates PDH/PDC

Answer 29

high levels of ADP and pyruvate

(low energy)

Question 30

regulation of cellular respiration by ADP levels is called

Answer 30

respiratory control or acceptor control

Question 31

when transfer of electrons is inhibited:

1. a decrease in the:
2. a decrease in the:
3. inhibition of _______ synthesis

Answer 31

1. pumping of protons
2. protein gradient
3. ATP

Question 32

some organisms can uncouple oxphos from ATP synthesis (by passes ATP synthesis); this is used to

Answer 32

generate heat and maintain body temperature (in hibernating animals)

Question 33

uncoupling of oxphos from ATP synthesis happens in

Answer 33

brown adipose tissue

(rich in mitochondria)

(reddish brown due to cytochromes and hemoglobin)

(new-born babies)

Question 34

inner mitochondrial membrane uncoupling proteins

Answer 34

UCP 1 (thermogenin)

(also UCP 2 and UCP 3) - play a role in energy homeostasis

Question 35

UCP 1 (thermogenin)

Answer 35

transfers protons from intermembrane space to matrix side; this energy is converted to heat instead of ATP

Question 36

how does UCP 1 work

Answer 36

allows protons to leak back into matrix (disrupts membrane integrity)

Question 37

brown adipose tissues is revealed upon

Answer 37

exposure to cold temperatures