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Biochemistry > Exam 2 Lecture 20 OxPhos > Flashcards

Exam 2 Lecture 20 OxPhos Flashcards

1
Q

What are the 2 membrane systems of the mitochondria

A

Outer and inner membrane

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2
Q

Why is the outer membrane permeable?

A

Presence of porin aka voltage dependent anion channel VDAC

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3
Q

Why is the inner membrane impermeable

A

Has metabolite transporters; very selective NADH and FADH2 are polar and use special transport

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4
Q

What are the 2 compartments of the mitochondria

A

Intermembrane space and matrix

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5
Q

Matrix of mitochondria is site of

A

TCA cycle and fatty acid oxidation

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6
Q

Ox Phos occurs where

A

In inner membrane

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7
Q

TCA cycle generates NADH and FADH2 which, in Ox Phos, flow through

A

4 protein complexes called the ETC

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8
Q

E-s reduce molecular O2 to

A

H20

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9
Q

Protons return to matrix by flowing through another complex called

A

ATP synthase

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10
Q

What is the mission of Ox Phos

A
  1. To transfer e-s from NADH and FADH2 to O2
  2. To establish proton gradient across the inner mito membrane
  3. To synthesize ATP
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11
Q

Electron flow is exergonic or endogonic?

A

Exergonic

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12
Q

Succinate Q reductase mechanism

A

Does not produce protons but moves protons from one complex to another

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13
Q

Succinate Q reductase has succinate dehydrogenase which

A

Generates FADH2 in TCA cycle

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14
Q

Complex I, III, and IV called

A

Respirasome

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15
Q

What are the 3 complexes that shuttle e-s from NADH to O2?

A
  1. NADH Q oxidoreducatase (complex I)
  2. Q cytochrome c oxidoreductase (complex III)
  3. Cyctochrome c oxidase (complex IV)
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16
Q

What are the 2 mobile e- carriers? Ie helpers?

A
  1. Coenzyme Q aka ubiquinone

2. Cytochrome c

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17
Q

Mechanism of coenzyme Q

A

Transfers e-s from NADH Q oxidoreductase and the Succinate Q reductase to Q cytochrome c oxidoreductase

E-s from complex I and II and transfers to complex III

18
Q

What makes coenzyme Q hydrophobic

A

Long tail made of 5 - C isoprene units

19
Q

Mechanism of cytochrome c

A

Shuttles e-s from Q cytochrome c oxidoreductase to cytochrome c oxidase

Ie shuttles e-s from complex complex III to complex IV

20
Q

Cytochrome catalyzes _

A

Reduction of O2

21
Q

What is the first point of entry of e-s from NADH

A

Complex I aka NADH dehydrogenase aka NADH-Q oxidoreductase

22
Q

Complex I is encoded by both _ and _ genes

A

Nuclear and mitochondrial genes

23
Q

Iron sulfur clusters undergo what reaction?

A

Redox; donates e-s

24
Q

Do protons leave iron sulfur clusters present in iron sulfur proteins?

A

No

25
Q

FADH2 enters the ETC through

A

Complex II aka succinate-Q reductase

26
Q

Complex II connects _ to Oxphos (succinate dehydroenase)

A

TCA

27
Q

Which complexes produce protons?

A

Complex I, III, and IV

28
Q

Does FADH2 leave complex II?

A

No, donates e-s; e-s will be moving foward not FADH2

  • e-s -> FeS -> Q to from QH2 *
29
Q

What is occurring in Complex III?

A

E-s from QH2 (complex II) are passed on to cytochrome c via complex III.

Flow of e-s through complex III leads to transport of 2 protons to cytoplasmic side

30
Q

What is happening in Complex IV, the final stage of the ETC cascade?

A

4 e-s are funned to O2 (final acceptor) to reduce it to H20. Concomitantly, protons are pumped from matrix to cytoplasmic side of inner membrane

31
Q

What is the 1 job of Cytochrome c Oxidase and what is it made of (structurally)?

A

One job is to transfer e-s; made of 2 heme and 3 Cu

32
Q

Free radical is a toxic derivative of _

A

Oxygen

33
Q

How are reactive oxygen species (ROS) formed?

A

By partial reduction of O2

34
Q

ROS include:

A
  • superoxide ion
  • peroxide ion
  • hydroxyl radical
35
Q

Mitochondria are a result of an _ event

A

An endosymbiotic event is thought to have occurred whereby a free-living organism capable of oxidative phosphorylation was engulfed by another cell.

36
Q

Superoxide dismutase (SOD) functions to do what?

A

cellular defense strategy that scavenges superoxide radicals by catalyzing the conversion of two of these radicals into hydrogen peroxide and molecular oxygen

37
Q

what is the function of catalse

A

takes the hydrogen peroxide formed from SOD and catalyzes the dismutation of hydrogen peroxide into water and molecular oxygen

38
Q

Glutathione peroxidase functions to

A

cellular defense as it scavenges hydrogen peroxide

39
Q

T/F: Vit E and C are other cellular defenses against oxidative damage

A

true. Vit E is lipophilic so is useful in protecting membranes from lipid peroxidation

40
Q

Eukaryotes contain 2 forms of SOD, which are:

A
  • Mn/Zn SOD present in mitochondria

- Cu/Zn SOD dependent cytoplasmic form

41
Q

transfer of a _ e- to O2 forms superoxide ion, whereas the transfer of _ e- yields peroxide

A

transfer of 1 e- = superoxide and transfer of 2 e-s = peroxide

42
Q

Glucose + 10NAD+ + 2FAD + 2(ADP + Pi) + 2 (GDP + Pi) ->

A

6CO2 + 10(NADH + H+) + 2FADH2 + 2ATP + 2GTP

THE OXIDATION OF FUELS (phase 1 of respiration)

10 NADH = 25 ATP (2.5 per H+)
2 FADH = 3 ATP (1.5 per H+)
2 GTP = 2 ATP
2 ATP = 2 ATP 
NET TOTAL = 32 ATP

Biochemistry (32 decks)

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