2.2.2. Phosphorylation

Question 1

Oxidative Phosphorylation Poisons: Electron Transport Inhibitors (there are four)

Answer 1

1) Rotenone
2) Cyanide
3) Antimycin A
4) Carbon Monoxide

Question 2

Oxidative Phosphorylation Poisons: ATP Synthase Inhibitors (there is one)

Answer 2

1) Oligomycin

Explanation: directly inhibits mitochondrial ATP synthase causing an increased proton gradient

Question 3

Oxidative Phosphorylation Posions: Uncoupling Agents

Answer 3

1) 2,4-dinitrophenol
2) aspiring overdose
3) thermogenin (brown fat)

Explanation: results in increased permeability of the membrane, causing decreased proton gradient and increased O2 consumption. ATP synthesis stops, but electron transport continues; produces heat.

Question 4

What is the final electron acceptor in the

ETC?

Answer 4

O2

Question 5

Complex I

Answer 5

NADH dehydrogenase

Question 6

Complex II

Answer 6

succinate dehydrogenase

Question 7

Complex III

Answer 7

cytochrome b-c1 complex or CoQ:C1 oxidoreductase

Question 8

Complex IV

Answer 8

cytochrome oxidase (O2–> H2O)

Question 9

Complex V

Answer 9

(F0F1 ATPase) ATP Synthase; couples the movement of H+ across the inner mito membrane to ATP synthesis from ADP + Pi

Question 10

Where does NADH pass its electrons to?

Answer 10

FMN (flavin mononucleotide)

Question 11

Where does FMN pass electrons to?

Answer 11

through a series of Fe-S centers to Coenzyme Q: accepts e- one at a time forming semiquinone, then ubiquinol (energy produced by e- transfers pumps H+ into cytosolic side of inner mito membrane)

Question 12

CoQ passes electrons to…

Answer 12

Cytochrome b and c1 through Fe-S centers

Question 13

Cytochrome c1 passes electrons to

Answer 13

cytochrome c; energy of e- transfers pumps H+ across the membrane

Question 14

Oxygen is reduced to water by…

Answer 14

electrons transferred from cytochrome aa3, which receives electrons from cytochrome c

Question 15

Where do the electrons from FADH2 enter the ETC?

Answer 15

Complex II; transfers election to CoQ without associated proton pumping across inner mito membrane

Question 16

ATP synthase conformations:

Loose

Answer 16

ADP + Pi

Question 17

ATP synthase conformations:

Tight

Answer 17

ATP

Question 18

ATP synthase conformations:

Open

Answer 18

release ATP

Question 19

__ ATP/NADH

Answer 19

2.5 ATP

Question 20

__ ATP/FADH2

Answer 20

1.5 ATP

Question 21

Why is cyanide poisonous?

Answer 21

CN blocks oxygen at the aa3 complex, so the ETC has no final electron acceptor

Question 22

MERRF

Answer 22

myotonic epilepsy & ragged red fibers

• faulty tRNA for leucine
• proliferation and aggregation of mitochondria
• progressive muscle weakness

Question 23

LHON: Leber Hereditary Optic neuropathy

Answer 23

90% caused by mutation of Complex I subunit

• maternally inherited
• acute optic atrophy with late onset, sudden presentation with blindness (15-35 yoa)

Question 24

MELAS

Answer 24

mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes

• faulty tRNA for lysine
• also ragged red fibers