Oxidative Phosphorylation

Front 1

What reduced cofactors yield most of the energy in the mitochondria?

Back 1

NADH and FADH2

Front 2

How many ATP does an FADH2 molecule form?

Back 2

1.5

Front 3

Where in the cell is ATPase found?

Back 3

The inner mitochondrial membrane

Front 4

In which direction are H+ pumped? Into or out of the mitochondrial matrix?

Back 4

Out, into the inter-membrane space.

Front 5

What type of gradient is set up by proton pumps? Electric or chemical?

Back 5

Trick question. Both are utilized as an electrochemical gradient.

Front 6

Which domain of ATPase is anchored in the inner mitochondrial membrane?

Back 6

Fo domain

Front 7

What subunit composes the ATPase "camshaft" and by how much does it rotate with the passage of a proton?

Back 7

the ϒ subunit, 120 degrees.

Front 8

How many protons are required to synthesize one molecule of ATP?

Back 8

3 must go through ATPase, but a total of 4 must be translocated into the matrix (one for Pi)

Front 9

What moves ATP out into the cytosol and ADP into the matrix?

Back 9

the ATP-ADP translocator (exchanger)

Front 10

What is translocated into the matrix along with Pi?

Back 10

H+

Front 11

What is the final electron acceptor?

Back 11

O2

Front 12

What is ΔE°' and what does it measure?

Back 12

The change in standard reduction potential, it measures the electron affinity of a molecule.

Front 13

What has the higher propensity for giving up electrons, NADH or O2? Is its E° positive or negative?

Back 13

NADH and negative, the more positive E°, the more it "wants" electrons (think positive attracts negative)

Front 14

What has a higher ΔE°' when donating electrons to O2, FADH2 or NADH? Is this value positive or negative? What about ΔG°'?

Back 14

NADH, negative, and also negative (thermodynamically favorable)

Front 15

What characteristic electron carriers do ETC proteins contain?

Back 15

flavin nucleotides, hemes, iron-sulfur clusters, and copper centers

Front 16

How many electrons can iron move at a time? What carrier accommodates for this?

Back 16

1. flavin nucleotides can move one or two electrons at a time.

Front 17

How are electrons physically carried in the ETC?

Back 17

Ubiquinone (CoQ) and cytochrome c (they're mobile)

Front 18

How many electrons can a ubiquinone transfer?

Back 18

1 (as a semiquinone) or 2 (hydroquinone)

Front 19

Is ubiquinone hydrophobic or hydrophilic? Cytochrome C?

Back 19

ubiquinone is hydrophobic and resides within the inner mitochindrial membrane. cytochrome c is hydrophilic and is on the surface of the membrane.

Front 20

What is the name of Complex 2?

Back 20

Succinate Dehydrogenase (the only TCA cycle protein)

Front 21

What ETC complexes pump H+?

Back 21

Complexes 1, 3 & 4

Front 22

How many hydrogen atoms are pumped into the matrix by the transport of 2 electrons through complex 1?

Back 22

4

Front 23

What role does glycerol-phosphate dehydrogenase play in the ETC?

Back 23

It can take the place of succinate dehydrogenase (complex 2) in donating electrons via the oxidation of FADH2

Front 24

From what proteins can ubiquinone accept electrons?

Back 24

complex 1, succinate dehydrogenase, glycerol-phosphate dehydrogenase, and fatty acyl-CoA dehydrogenase.

Front 25

What is the name for complex 3?

Back 25

cytochrome reductase

Front 26

Why do are flavins worth less energy than NADH?

Back 26

They skip complex 1, yielding 2 fewer H+ pumped per electron

Front 27

What carries electrons between complexes 3 and 4?

Back 27

cytochrome c

Front 28

What is the substrate for cytochrome oxidase?

Back 28

cytochrome c is the substrate for complex 4 (aka cytochrome oxidase)

Front 29

How many H+ are pumped by the passage of 2 electrons through complex 3? Complex 4?

Back 29

4 by complex 3, 2 by complex 4

Front 30

Starting with NADH, how many protons can be pumped by the ETC? How about FADH2?

Back 30

10 from NADH, 6 from FADH2

Front 31

Through what must NADH give up its electrons to before they're passed on to iron centers?

Back 31

FMN because NADH can only give up 2 electrons at a time, whereas iron centers can only accept them one at a time

Front 32

Percentage-wise, about how efficient is oxidative phosphorylation?

Back 32

50% (the rest is lost as heat)

Front 33

How do electrons transfer from complex 2 to complex 3?

Back 33

ubiquinone

Front 34

What is the final center in complex 4 that donates electrons to oxygen?

Back 34

cytochrome A3 copper B binuclear electron center

Front 35

rotenone

Back 35

inhibits complex 1, an insecticide from plants

Front 36

amytal

Back 36

inhibits complex 1, a barbiturate

Front 37

antimycin

Back 37

inhibits complex 3, an antibiotic

Front 38

cyanide

Back 38

inhibits complex 4

Front 39

Everything downstream of an inhibited complex will be reduced or oxidized?

Back 39

oxidized

Front 40

Will ubiquinone be oxidized or reduced with the addition of antimycin?

Back 40

reduced

Front 41

How is malate a source of electrons for NADH?

Back 41

malate dehydrogenase -> OAA -> NADH

Front 42

What happens when succinate is supplied to rotenone-treated cells? Cyanide-treated?

Back 42

succinate will add electrons to the ETC via complex 2, so a cell treated with rotenone (inhibits complex 1) will survive whereas cyanide (inhibits complex 4) will not

Front 43

What processes can become uncoupled?

Back 43

transfer of electrons and ATP synthesis

Front 44

When does ATPase become active and collapse the proton gradient?

Back 44

When there is a high concentration of its respiratory regulator, ADP

Front 45

What causes the ETC to start pumping protons?

Back 45

when the H+ gradient is collapsed

Front 46

What is brown adipose?

Back 46

contains thermogenin, a H+ channel which collapses the H+ gradient and releases energy in the form of heat, bypassing ATPase

Front 47

Are electrons being transferred when oxidative phosphorylation is uncoupled

Back 47

Yes, because the H+ concentration is being collapsed

Front 48

What four things are required for ATP synthesis (other than basic cellular machinery)?

Back 48

electron donor, O2, ADP and Pi

Front 49

What is at a physiological higher concentration, ADP or Pi?

Back 49

Pi, which is why ADP is the respiration regulator

Front 50

oligomycin

Back 50

inhibits the H+ channel in ATPase

Front 51

2,4-dinitrophenol

Back 51

an uncoupler, it can be protonated in the inner mitochondrial space and diffuses through the lipid bilayer (b/c it's nonpolar) and then deprotonates in the mitochondrial matrix, effectively collapsing the H+ gradient

Front 52

Is O2 consumed in an uncoupled ETC?

Back 52

Yes because electron transport is functioning to restore the collapsed H+ gradient