ETC Review

Question 1

ATP from substrate-level phosphorylation

Answer 1

Glycolysis
TCA

Question 2

TCA Stage 1

Answer 2

Acetyl-CoA production

Question 3

TCA Stage 2

Answer 3

Acetyl-CoA oxidation

Question 4

TCA Stage 3

Answer 4

Electron transfer and oxidative phosphorylation

Question 5

Oxidative Phosphorylation

Answer 5

Mitochondria

Produces most ATP

FADH2 & NADH: electron carriers
-oxidized at ETC
–proton gradient
—synthesize ATP

Question 6

Mitochondrial Oxidative Phosphorylation

Answer 6

1. Respiratory ETC
2. ATP synthase uses the proton gradient energy

Question 7

NADH vs FADH2

Answer 7

Both coenzymes

NADH:
cosubstrate
can move
3 ATP

FADH2:
prosthetic group
can’t move
2 ATP

Question 8

Complex I

Answer 8

NADH gives electrons to Complex 1, which oxidizes NADH

Transfers electrons to ubiquinone (Q, coenzyme Q)

Protons to ATP synthase

Question 9

Complex II

Answer 9

Succinate —> fumarate in TCA produces FADH2

Gives electrons to Complex II

Transfers electrons to ubiquinone (Q, coenzyme Q)

Does not produce enough energy to transfer protons

Question 10

Ubiquinone (Q, Coenzyme Q)

Answer 10

Electron carrier

Transfers electrons to Complex III

Transfers protons from matrix to inter membrane space

Question 11

Complex III

Answer 11

Transfers electrons to cytochrome c

Protons to ATP synthase

Question 12

Cytochrome c

Answer 12

Electron carrier

Transfers electrons to Complex IV

Question 13

Complex IV

Answer 13

Transfers electrons to 1/2 O2

O2 reduced to H2O

Protons to ATP synthase

Question 14

Complex V

Answer 14

ATP synthase

Question 15

Where are the five oligomeric assemblies of proteins associated with oxidative phosphorylation found?

Answer 15

Inner mitochondrial membrane

Question 16

Redox Reactions: Highest Reduction Potentials

Answer 16

O2 has highest reduction potential (most + Eº’(V))

Most likely to be reduced (gain electrons)

Good oxidizing agents

Highest reduction potential will be reduced as written (will flip/reverse other reactions)

Question 17

Reduced

Answer 17

Gain H

Question 18

Most Reduced Form of Carbon

Answer 18

CH4 – methane

Question 19

Most Oxidized Form of Carbon

Answer 19

CO2 – carbon dioxide

Question 20

Flow of Electrons in Complex I

Answer 20

NADH –> FMN –> Fe-S —-> CoQ

Question 21

Flow of Electrons in Complex II

Answer 21

Succinate –> FAD –> Fe-S —-> CoQ

Question 22

Flow of Electrons in Complex III

Answer 22

CoQ —-> Fe-S / cyt b –> cyt c1 —-> cyt c

Question 23

Flow of Electrons in Complex IV

Answer 23

cyt c —-> cyt a –> cyt a3 —-> O2

Question 24

Redox Centers: Flavins

Answer 24

From riboflavin, vitamin B2

FAD & FMN

Carries 2 electrons

Prosthetic groups (can’t move)

Question 25

Redox Centers: Iron-Sulfur Complexes

Answer 25

Fe2S2 & Fe4S4

Question 26

Redox Centers: Ubiquinone (Q, Coenzyme Q)

Answer 26

Carries 1 electron at a time

Complete reduction of ubiquinone requires 2 electrons and 2 protons, and occurs together in two steps through the semiquinone radical intermediate

Question 27

Redox Centers: Cytochrome C

Answer 27

Cytochromes are electron carrying proteins with a heme prosthetic group

Only carries electrons, not protons

Question 28

Chemiosmotic Model

Answer 28

Chemical potential ∆pH (inside alkaline)
—–>
ATP synthesis driven by proton-motive force
<—–
Electrical potential ∆w (inside negative)