EXAM 3: OXPHO

Question 1

carbs, lipids, amino acids are the main…

Answer 1

reduced fuels for the cell

Question 2

in oxidative phosphorylation,

Answer 2

energy from NADH and FADH2 are used to make ATP

Question 3

if a prokaryote lives in an oxygenate environment,

Answer 3

oxidative phosphorylation can be done using the plasma membrane

Question 4

energy of oxidation is used to

Answer 4

phosphorylate ADP

Question 5

chemiosmotic theory

Answer 5

series of energy translations that results in energy for phosphorylation of ADP

Question 6

energy released by electron transport…

Answer 6

is used to transport protons against the electrochemical gradient

favorable redox reactions are used to make this gradient

Question 7

energy needed to phosphorylate ADP is provided by the

Answer 7

flow of protons down the electrochemical gradient

not result of a direct reaction

Question 8

bacteria

Answer 8

plasma membrane

Question 9

mitochondria

Answer 9

inner membrane

Question 10

chloroplasts

Answer 10

thylakoid membrane

Question 11

four distinct compartments of double membrane

Answer 11

outer

IMS

inner membrane

matrix

Question 12

Outer membrane

Answer 12

relatively porous membrane, allows passage of metabolites

Question 13

IMS

Answer 13

similar to cytosol; higher proton concentration, lower pH

Question 14

inner membrane

Answer 14

relatively impermeable, proton gradient across it

location of electron transport chain complexes (including succinate dehydrogenase as part of Complex II)

infolding of membrane produces cristae - serves to increase surface area

Question 15

matrix

Answer 15

location of CAC and parts of lipid and amino acid metabolism

lower proton concentration, higher pH

Question 16

electron transport chain complexes

Answer 16

each complex (4) have multiple redox centers with:

FMN/FAD

cytochromes a,b,or c

iron-sulfur clusters and heme groups

Cu centers and FeCu centers

Question 17

FMN / FAD

Answer 17

FMN: complex 1
FAD: complex 2

initial electron acceptors

can carry two electrons but transfer one at a time

Question 18

iron-sulfur centers

Answer 18

one electron carriers

coordinated by stationary cysteines in the protein

contain variable numbers of iron and sulfur atoms; multiple ions, multiple transfers

Question 19

cytochromes

Answer 19

proteins or subunits of complexes containing heme prosthetic groups

one electron carriers

iron coordinating porphoryin ring derivatives ring determines cytochrome type)

can be mobile or stationary

Question 20

coenzyme Q

Answer 20

ubiquinone

Question 21

ubiquinone

Answer 21

lipid-soluble conjugated dicarbonyl compound that readily accepts electrons

transfer 1 or 2 electrons at a time

upon accepting 2 electrons, picks up two H+ —> ubiquinol

Question 22

ubiquinol

Answer 22

can freely diffuse in the membrane, carrying electrons with protons

mobile electron carrier transporting electrons from Complex 1 or 2 to 3

Question 23

ubiquinone

Answer 23

Q

oxidized, hydrophobic tail in membrane

Question 24

ubiquinol

Answer 24

QH2

fully reduced

Question 25

free energy of electron transport

Answer 25

electrons are spontaneously transferred from molecules with lower reduction potentials to molecules with higher reduction potentials the free energy released is used to pump protons, storing this energy as the electrochemical gradient

Question 26

COMPLEX 1 NADH: ubiquinone oxidoreductase

Answer 26

large; over 40 diff pp chains encoded by nuclear and mitochondrial DNA

Question 27

COMPLEX 1 process

Answer 27

NADH binding site on matrix side of membrane FMN noncovalently bound, accepts 2 electrons from NADH passes one at a time to iron-sulfur clusters several iron sulfur clusters pass one electron at a time to ubiquinone binding site within the membrane ubiquinone is reduced to ubiquinol 2 electrons from NADH to Q is accompanied by a transfer of 4 protons from the matrix (N) to intermembrane space (P) via transporters reduced Q picks up 2 H+

Question 28

COMPLEX II: SUCCINATE DEHYDROGENASE

Answer 28

succinate oxidized to fumarate FAD accepts 2 electrons from succinate to make FADH2 electrons passed one at a time via iron sulfur centers to Q which picks up 2 H+ to become QH2

Question 29

net protons pumped at complex 1

Answer 29

4; 2 picked up for QH2

Question 30

net protons pumped at complex 2

Answer 30

0 2 dropped off by FADH2 2 picked up by Q

Question 31

why do you only get 2.5 ATP from NADH and only 1.5 ATP from FADH2?

Answer 31

NADH at complex 1 pumps 4 protons to the IMS while at complex 2 there are 0 protons pumped/ the gradient is not affected

Question 32

COMPLEX III: UBIQUINONE; CYTOCHROME C OXIDOREDUCTASE

Answer 32

2 electrons from QH2 to reduce 2 molecules of cytochrome C iron sulfur clusters, cytochrome b, cytochrome c Q CYCLE: 4 additional protons added to IMS

Question 33

THE Q CYCLE

Answer 33

4 protons are added to the IMS per two electrons that reach cytochrome c ``` ________ 2 molecules of QH2 become oxidized 2 cytochrome c reduced 2 protons from each QH2 goes to IMS 1 Q gets reduced using 2 electrons from QH2 oxidation 2 protons from the matrix reduce Q ```

Question 34

Q CYCLE PROCESS

Answer 34

Q, QH2, C bind QH2 oxidizes, e goes to Q, e goes to C, 2H+ goes to IMS C is reduced, leaves to complex 4; oxidized Q leaves; Q* stays new QH2 binds, new C binds QH2 oxidizes, e goes to Q*, e goes to C, 2H+ go to IMS 2H+ go to Q*+e C is reduced, goes to complex 4; oxidized Q leaves; reduced QH2 leaves

Question 35

q cycle overall

Answer 35

``` 2 cyto c reduced 4 protons to IMS 2 protons out of matrix oxidized 2 Q reduced 1 QH2 ``` net equation: QH2 + 2cytC (ox) + 2H+n = Q + 2 cytC (red) + 4H+p

Question 36

cytochrome c

Answer 36

second mobile electron carrier soluble heme containing protein in the IMS heme iron can be oxidized (3+) or reduced (2+) carries single electron from Complex III to Complex IV

Question 37

COMPLEX IV: CYTOCHROME OXIDASE

Answer 37

13 subunit membrane protein 2 heme groups; a, a3 copper ions at 2 sites; CuA, CuB

Question 38

CuA

Answer 38

two ions that accept electrons from cyto c

Question 39

CuB

Answer 39

bonded to heme a3; forming binuclear center that transfers 4 electrons to oxygen

Question 40

passing of electrons to O2 in complex 4

Answer 40

4 cytochrome C reduced from complex 3 bring electrons to complex 4 and are oxidized 4 electrons used to reduce 1 oxygen to make 2 water molecules 4 H+ picked up from the matrix; helps build gradient 4 H+ additional are pumped from matrix to IMS reduction of O2 provides enough energy to remove 4H+ from matrix AND pump 4 H+ to IMS

Question 41

reducing oxygen equation

Answer 41

½ O2 —> H2O 2 cyto C 2 e- 2 H+ substrate 2 H+ pumped

Question 42

Complex 1 to complex 4

Answer 42

NADH + 11 H+n + ½ O2 = NAD+ + 10H+p + H2O 2.5 ATP dG = -220kJ/mol

Question 43

Complex 2 to complex 4

Answer 43

FADH2 + 6H+n + ½ O2 = FAD+ + 6H+p + H2O 1.5 ATP dG = -150 kJ/mol (less energy from transport, less protons to IMS, less ATP made)

Question 44

proton motive force

Answer 44

proteins in the ETC created the electrochemical proton gradient by 1 of 3 means 1. actively transporting protons across the membrane (Complex 1, Complex IV) 2. chemically removing protons from the matrix (Complex 3 reduction of Q, reduction of oxygen Complex IV) 3. release of protons into the IMS (Oxidation of 2 QH2 in Complex III)

Question 45

chemiosmotic model for ATP synthesis

Answer 45

electron transport sets up a proton-motive force energy of proton-motive force drives synthesis of ATP via controlled release

Question 46

CN-

Answer 46

blocks electron transfer to oxygen; ATP synthesis is shut down because electron transport is shut down, there is no energy from electron transport driving the proton gradient

Question 47

oligomycin

Answer 47

inhibits ATP synthesis; shuts down electron transport as well because ATP synthesis dissipates the proton gradient

Question 48

DNP

Answer 48

uncouples reactions; equalizes H+ concentrations across the membrane by allowing the gradient to dissipate O2 is still consumed and protons are pumped to the IMS but ATP synthesis does not occur

Question 49

mitochondrial ATP synthase complex

Answer 49

2 functional units: F1, F0

Question 50

F1

Answer 50

soluble complex in the matrix catalyzes synthesis from ADP and Pi

Question 51

F0

Answer 51

integral membrane complex transports H+ from IMS to matrix, dissipating gradient energy transfers to F1 to catalyze phosphorylation of ADP

Question 52

F1 hexamer

Answer 52

arranged in 3 alpha-beta dimers dimers have 3 conformations beta empty: nothing bound beta ADP: ADP and Pi bound loosely beta ATP: catalyzes ATP formation by binding product tightly

Question 53

synthase

Answer 53

no ATP

Question 54

synthetase

Answer 54

ATP

Question 55

coupling proton translocation to ATP synthesis

Answer 55

proton translocation causes a rotation of the F0 and the central shaft gamma subunit rotation of the shaft causes a conformational change within all three alpha-beta pairs the conformational change in one of the 3 pairs promotes the condensation of ADP and Pi into ATP the biggest conformational change allows ATP to leave because it was previously tightly bound

Question 56

adenine nucleotide translocase

Answer 56

antiporter; ATP4- in IMS, ADP3- in matrix

Question 57

phosphate translocase

Answer 57

symporter phosphate, H+ into matrix

Question 58

2 ways to get NADH from cytosol into mitochondria glycolysis to ETC

Answer 58

malate aspartate shuttle glycerol 3P shuttle

Question 59

malate aspartate shuttle

Answer 59

electrons given to malate via malate dehydrogenase which has transporter into matrix where NADH is regenerated aspartate is transported out to cytosol to continue shuttle NADH goes through complex I to get 2.5 ATP for each NADH malate + NAD+ —> oxaloacetate —> aspartate —> oxaloacetate + NADH... malate dehydrogenase; aspartate aminotransferase

Question 60

glycerol 3P shuttle

Answer 60

electrons given to dihydroxyacetone phosphate (ox) to make glycerol 3P (red) —> glycerol 3P dehydrogenase (cytosolic) oxidation of glycerol-3P back to DHAP reduces FAD to FADH2 —> glycerol 3P dehydrogenase (mitochondrial) electrons transferred from FADH2 to Q —> QH2 which goes to complex 3 to get 1.5 ATP for each FADH2

Question 61

regulation of OXPH

Answer 61

substrate availability: NADH or FADH2 and ADP/Pi due to coupling: substrates required for both ETC and ATP synthesis inhibition leads to accumulation of NADH —> inhibits enzymes in glycolysis, CAC inhibitor of F1

Question 62

IF1

Answer 62

ATP synthase can work in reverse when there is no proton gradient IF1 works in matrix; prevents hydrolysis of ATP during low oxygen by preventing ATPase from turning backwards active at lower pH when electron transport is stalled due to low O2 and H+ remains in matrix