Exam 2 Lecture 21 Regulation of OxPhos

Question 1

in regulation of OxPhos, e-s flows from the molecules with _ E0’ to that with the _ E0’

Answer 1

flow from molecules with lower E0’ to that with the highest E0’

E0’ = standard redox potential

Question 2

what are the 2 factors that govern the pmf to drive ATP synthesis by Complex V

Answer 2

1. chemical/pH gradient ( protons are responsible for low pH)
2. charge gradient/membrane potential (need intact, non-leaky mem for pos charge)

Question 3

peter mitchell suggested the chemiosomotic hypothesis to propose what:

Answer 3

proposed that e- transport and ATP synthesis are coupled by a proton gradient across the inner mitochondrial membrane

Question 4

what are the details peter mitchell’s proposed model?

Answer 4

the transfer of e-s through the respiratory chain leads to pumping of H+s from the matrix to the cytoplasmic side of the inner mito mem. The H+ conc becomes lower in the matrix, creating a neg field in the matrix, and H+s flow back into matrix to equalize

Question 5

the inner mito mem is _ to H+ and OH- ions

Answer 5

impermeable to these ions so the pmf can be established

Question 6

ATP synthase/Complex V is embedded in the inner mito membrane.
The F0 subunit is for:
The F1 subunit is for:

Answer 6

F0 unit spans the inner mito mem and contains a proton channel
F1 unit protrudes into the mito matrix and contains the catalytic activity of the synthase

Question 7

the 5 subunits of F1, which ones have a specific purpose?

Answer 7

alpha and beta subunits bind nucleotides (ATP/ADP) but only beta is catalytically active; the gamma subunit breaks symmetry of the a3B3 hexamer

Question 8

the formation of the cristae allows:

Answer 8

the proton gradient to be in close proximity to ATP synthase for ehancement of ATP synthesis

Question 9

1 mole of ATP requires:

Answer 9

3 + 1 H+ passage

Question 10

the role of the proton gradient is not to form ATP but to:

Answer 10

release it from the synthase

Question 11

oligomycin does what?

Answer 11

disrupts proton transport through the channel

Question 12

4 protons enter through the intermembrane space and _n are used

Answer 12

3 are used

Question 13

ATP and ADP are not permeable across mitochondrial mem thus needs _

Answer 13

a carrier ie ATP-ADP translocase family

Question 14

The flow of ATP and ADP is coupled which means:

Answer 14

ADP enters the matrix only if ATP leaves

Question 15

Reduced NADH cannot cross the mitochondrial membrane, thus what are the 2 shuttle systems?

Answer 15

1. malate-aspartate shuttle (Complex I)

2. glycerophosphate shuttle (CoQ)

Question 16

malate-aspartate shuttle operates in:

Answer 16

heart, liver, and kidneys

Question 17

malate-aspartate shuttle generates NADH in _

Answer 17

in mito-matrix

Question 18

in the malate-aspartate shuttle, NADH enters to ETC at _

Answer 18

complex I

Question 19

glycerophosphate-shuttle operates in:

Answer 19

skeletal muscle and brain

Question 20

glycerophosphate-shuttle generates FADH2 in the _

Answer 20

inner mito-membrane

Question 21

in the glycerophosphate-shuttle, FADH2 joins to ETC at _

Answer 21

CoQ

Question 22

levels of _ regulate respiration

Answer 22

ATP

Question 23

T/F: e-s flow through ETC only when ADP phosphorylated to ATP

Answer 23

true; e-s do not flow through the ETC to O2 unless ADP is simultaneously phosphorylated to ATP

Question 24

regulation of ADP levels is called:

Answer 24

respiratory control or acceptor control ex when ADP conc rises in active muscle the rate of OxPhos rises to meet ATP needs of the muscle

Question 25

Inhibition of OxPhos happens when:

Answer 25

when transfer of e-s is inhibited ie:

• a decr in the pumping of protons
• a decr in the proton gradient
• inhibition of ATP synthesis

Question 26

uncoupling OxPhos from ATP synthesis to generate heat happens in _

Answer 26

brown adipose tissue

Question 27

in brown adipose tissue, the inner mito-membrane contain uncoupling protein:

Answer 27

UCP 1 aka thermogenin

Question 28

thermogenin transfers protons from to where?

Answer 28

transports protons from the cytoplasm to the matrix with the assistance of FAs

cytoplasm -> intermembrane space -> matrix

Question 29

about _ molecules of ATP are formed when glucose is completely oxidized to CO2

Answer 29

30

Question 30

Most of the ATP, _ of 30 molecules formed when glucose is oxidized to CO2, is generated by OxPhos

Answer 30

26 from OxPhos

Question 31

thermogenin generates heat by permitting the influx of protons into the mitochondria without _

Answer 31

the synthesis of ATP

Question 32

Iron-sulfur centers

Answer 32

• Present in complex I, II, III (covalently attached)
• Fe-S centers are non-heme acceptors/donors of e-s
• diseases associated w defects in biogenesis of Fe-S centers