Chapter 20 (Complexes)

Question 1

Complex I

Answer 1

NADH Dehydrogenase
Electron transfer from NADH to the mobile protein CoQ
Redox centers are: FMN and Fe-S clusters
Four H+ transported out per 2e-

Question 2

___ bridges the gap between NADH (only 2e- at a time) and Fe (only 1e- at a time)

Answer 2

FMN

Question 3

Overall equation for Complex I

Answer 3

NADH + H + CoQ (goes to) NAD + CoQH2

Highly exergonic

Question 4

Complex I has enough energy to synthesis ___ when e- come back in

Answer 4

ATP

-81 kJ/mol

Question 5

Complex II

Answer 5

Succinate Dehydrogenase

Oxidation of FADH2 by CoQ

Question 6

Only e- from ___ can enter into Complex II

Answer 6

Succinate

Question 7

Overall equation for Complex II

Answer 7

Succinate + CoQ (goes to) Fumarate + CoQH2

Only slightly exergonic so NO H+ is pumped into the matrix during this step

Question 8

Complex II (does/does not) contribute to the proton gradient

Answer 8

does not 
(not enough Delta G knot)

Question 9

___ can only enter via Complex I

Answer 9

Matrix NADH

Question 10

Regardless of where an e- enters (either Complex I or II) it will always end up in the ___

Answer 10

UQ/UQH2 pool

Question 11

Before the e- enter Complex III the only Complex that translocates protons (H+) up till this point is Complex ___

Answer 11

I

Question 12

Complex III

Answer 12

CoQ-Cytochrome c Oxidoreductase

Passes e- from reduced CoQ to cytochrome c (carries only 1e- at a time)

Question 12

Complex III

Answer 12

CoQ-Cytochrome c Oxidoreductase

Passes e- from reduced CoQ to cytochrome c (carries only 1e- at a time)

Question 13

In Complex III the oxidation of one ___ is accompanied by the translocation of ___ H+ across the ___ membrane

Answer 13

UQH2
4
inner mitochondrial

Question 13

In Complex III the oxidation of one ___ is accompanied by the translocation of ___ H+ across the ___ membrane

Answer 13

UQH2
4
inner mitochondrial

Question 14

UQ-

Answer 14

semiquinone form

Question 14

UQ-

Answer 14

semiquinone form

Question 15

The Qp site in Complex III is located closer to the ___

Answer 15

intermembrane space

Question 15

The Qp site in Complex III is located closer to the ___

Answer 15

intermembrane space

Question 16

Complex IV

Answer 16

Cytochrome c Oxidase
Cytochrome c drops off 1e- and oxidzes 1/2O2 into H2O
utilizes 2 hemes and 2 Cu sites
linear electron transfer

Question 16

The Qn site in Complex III is located closer to the ___

Answer 16

Matrix

Question 17

The Q cycle takes place in Complex ___

Answer 17

III

Question 18

First half of Q cycle

Answer 18

UQH2 leaves the pool and donates 1e- to cytochrome c in the Qp site (resulting in the translocation of 2 H+) and becomes UQ-
UQ- last e- goes to the Qn site (resulting in UQ which goes back into pool)
A UQ from the pool enters the Qn site and takes the 1e- that came from the Qp site (resulting in a UQ-

Question 19

Second half of Q cycle

Answer 19

UQH2 leaves the pool and donates 1e- to cytochrome c in the Qp site (resulting in the translocation of 2 H+) and becomes UQ-
UQ- last e- goes to the Qn site (resulting in UQ which goes back into pool)
The UQ- from the first half take the 1e- that came from the Qp site as well as 2H+ from the matrix and becomes UQH2 (which then enters back into the pool)

Question 20

Formal name for Complex IV

Answer 20

Cytochrome c Oxidase

Question 21

___ is the terminal acceptor of e- in the ETC pathway

Answer 21

Oxygen

Question 22

The complete reduction of O2 requires ___ e-

Answer 22

4

Question 23

Complex IV transports ___ H+ for every 1e-

Answer 23

1

Question 24

Complex IV uses ___ radicals, so if the complex is “leaky” this will result in:

Answer 24

super oxide

damage to the cells

Question 25

Mitochondrial NADH proton transfers through:
I
II
III
IV

Answer 25

I: 4H+
II: (isn't used)
III: 4H+
IV: 2H+
Total of 10H+

Question 26

Succinate (FADH2) proton transfers through:
I
II
III
IV

Answer 26

I: (isn't used)
II: (no protons transfered)
III: 4H+
IV: 2H+
Total of 6H+

Question 32

___can only enter via Flavoprotein 4

Answer 32

Cytosolic NADH (via Glycerol Phosphate Pathway)

Question 33

The FAD in Complex ___ is covalently attached to a ___

Answer 33

II

His residue