The Electron Transport Chain, ATP Synthesis, and Mitochondrial Shuttles

Question 1

Complex I:

Answer 1

NADH-Q oxidoreductase (it pumps 4 protons from NADH donates to Q) Contains FMN and two kinds of Fe-S clusters (2Fe-2S and 4Fe-4S) in which the iron cycles between +2 and +3 oxidation states

Source of NADH: : TCA cycle, fatty acid b-oxidation, amino acid catabolism

Question 2

Complex III

Answer 2

Q-cytochrome c oxidoreductase (it pumps 4 protons) Receives electrons from complexes I and II via QH2

Question 3

Complex IV:

Answer 3

cytochrome c oxidase

Question 4

Complex II:

Answer 4

succinate-Q reductase (does not pump protons)

Question 5

A supramolecular complex involving complexes I, II, and III

Answer 5

respirasome

Question 6

Consist of different oxidized states of Coenzyme Q (Q and QH₂)

Answer 6

Q-pool

Question 7

The first electron accepter in Complex I

Answer 7

FMN (flavin mononucleotide)

Question 8

Contains TCA cycle flavoprotein succinate dehydrogenase

Answer 8

Complex II

Question 9

Electron pair from FADH2 can generate only ____ ATPs vs _____ for NADH

Answer 9

1.5; 2.5

Question 10

Complex III contains three ______groups

Answer 10

heme (bL, bH, c1)

Question 11

Contains 2 heme a groups (a and a₃) and 2 copper centers (Cu_A Cu_B)

Answer 11

Complex IV Oxygen binds between heme a3 and CuB. It forms a peroxide bridge, and is reduced to the peroxyl derivative and then converted to water using four “substrate” protons

Question 12

Contains catalytic activity of ATP Synthase

Answer 12

F1

Question 13

Part of F₁ that rotates and contains long helical coiled-coil that extends into hexamer and breaks it symmetry

Answer 13

gamma subunit connected to the C-ring of the F_{<span>0</span>} subunits

Question 14

Asymmetric distribution of protons provides a

Answer 14

“proton-motive force”

Question 15

Each proton pump give about _____ of free energy

Answer 15

20 kJ/mol

Question 16

At ATP synthase ATP and ADP are at _______

Answer 16

equilibrium

Question 17

Only _____ subunits of F₁ are catalytically active

Answer 17

ß

Question 18

How many ATPs are made per 360 degree rotation of gamma subunit

Answer 18

3 ATPs

Question 19

The Glycerol 3-Phosphate (glycerol-3-phosphate dehydrogenase) shuttle is prevalent in _____

Answer 19

muscle

uses FADH₂ and is present on the outer (cytoplasmic) surface of inner membrane and donates to electrons to Q

Allows transport against [NADH] gradient

Question 20

How many moles of ATP made per mole of glucose?

Answer 20

30 moles of ATP

Question 21

Last electron acceptor

Answer 21

Oxygen

Question 22

Blocks flow through complex III.

Answer 22

Antimycin A

Question 23

Block e-flow through complex I

Answer 23

Rotenone, amytal

Question 24

Inhibition of ATP synthase

Answer 24

Oligomycin, dicyclohexylcarbodiimide

Question 25

genetic mutation in genes of one of the subunits of Complex 1 (ND1, ND4, ND6). Can lead to blindness in middle age

Answer 25

Leber's Hereditary Optic Neuropathy (LHON) Diagnosis can be confirmed by a genetic test. Mutation effects nervous system; cause death of optic nerve

Question 26

How many subunits of Complex 1 are encoded by mitochondrial genes?

Answer 26

Seven

Question 27

How many people worldwide are affected by low vision due to LHON

Answer 27

About 3500

Question 28

largely permeable membrane with many copies of VDAC

Answer 28

outer membrane

Question 29

largely impermeable membrane that has various shuttles or transporters

Answer 29

inner membrane

Question 30

Mitochondrion arose during endosymbiotic event involving \_\_\_\_\_.

Answer 30

alpha-proteobacterium

Question 31

Hydrophobic molecule that diffuses rapidly within membrane (long tail contains ten 5-carbon isoprene units)

Answer 31

Ubiquinone (Coenzyme Q) Accepts e-'s from complexes I & II; shuttles back and forth between thes donors and acceptors

Question 32

Sources of NADH

Answer 32

TCA cycle, fatty acid Beta-oxidation, amino acid catabolism

Question 33

Electron carriers of the ETC

Answer 33

Coenzyme Q and cytochrome c

Question 34

Contains heme group (heme b) that does not receive electrons, but protects against formation of ROS

Answer 34

Complex II

Question 35

Contains two types of cytochromes (b and c1) with three hemes (bL, b_H, and c₁- all protoporphyrin IX type and a Rieske 2Fe-2S center)

Answer 35

Q-Cytochrome c oxidoreductase (Complex III, Cytochrome reductase)

Question 36

Contains 13 subunits, but only 3 are critical for e- flow

Answer 36

Complex IV

Question 37

ATP Synthase

Answer 37

F₁F₀ ATPase

Question 38

F1 subunits

Answer 38

alpha3, beta3, gamma, delta, and sigma

Question 39

Coupling between respiratory chain and ATP Synthesis is \_\_\_\_\_\_\_\_.

Answer 39

"obligatory" ----can't have one without the other

Question 40

T, O, and L configurations of beta subunits in F1

Answer 40

T: tight (binds ATP very tightly O: open (can bind or release ADP or ATP) L: loose (binds ADP, Pi)

Question 41

Chemical uncouplers

Answer 41

2,4-dinitrophenol e- transport can proceed, but ATP synthesis cannot

Question 42

Inhibition of ATP-ADP tranlocase

Answer 42

Atractyloside, bongkrekic acid

Question 43

Inhibits cytochrome oxidase

Answer 43

CN^-, N₃^- (azide), CO

Question 44

The F_{0 ____ subunit is stationary (stator) while the "c" subunits for a membrane- spanning ring that can rotate (rotator)}

Answer 44

a subunit contains two hydrophobic half-channels that do not span the membrane (each channel interacts with one "c" subunit)

Question 45

\_\_\_\_\_\_\_\_(AA) is in the center of "c" subunit

Answer 45

Aspartic acid residue (Asp-61)

Question 46

How many "c" subunits are present in F₀?

Answer 46

10

Question 47

No direct transporters for:

Answer 47

NADH, acetyl-CoA and oxaloacetate

Question 48

Phosphate carrier and ATP-ADP translocase and synthase together form large \_\_\_\_

Answer 48

ATP synthasome

Question 49

Shuttle mainly present in heart and liver

Answer 49

malate-aspartate shuttle Another way of getting electrons from cytosolic NADH into mitochondrial matrix Involves transport of malate/alpha-ketoglutarate and aspartate/glutamate across membrane

Question 50

Other shuttles (carriers): * Dicarboxylate * Tricarboxylate * Pyruvate

Answer 50

* phosphate/malate * malate/citrate * pyruvate/OH^-

Question 51

Some organisms can uncouple e- transport from ATP synthesis to generate \_\_\_\_

Answer 51

heat ex. Brown adipose tissue (contains lots of uncoupling protein, UCP-1 (thermogenin)) "nonshivering theromogenesis

Question 52

Electrons passed down chain in order of

Answer 52

increasing reduction potential -- highly exergonic process

Question 53

Energy released from ETC ultimately fuels

Answer 53

synthesis of ATP

Question 54

Three large complexes that pump electrons

Answer 54

* Complex I: NADH-Q oxidoreductase * Complex III: Q-cytochrome c oxidoreductase * Complex IV: cytochrome c oxidase

Question 55

Hydrophobic molecule that diffuses rapidly within membrane (long tail contains ten 5-carbon isoprene units)

Answer 55

Ubiquinone