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2) Biochemistry II > Oxidative Phosphorylation > Flashcards

Oxidative Phosphorylation Flashcards

1
Q

Energy from ________ is used to synthesize ATP

A

reduced fuels (CHO, lipids, AA)

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2
Q

What is used as an energy source?

A

Electrons from NADH or FADH2

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3
Q

Oxidative phosphorylation involves reduction of ___ to ___ using electrons donated from ____ and _____

A

O2
H2O
NADH
FADH2

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4
Q

Which cellular structure can synthesize its own proteins?

A

Mitochondria since it has its own DNA

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5
Q

What is the oxidized form of coenzyme Q called?

A

Ubiquinone

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6
Q

What is the reduced form of coenzyme Q called? How many electrons and hydrogens does it have?

A
  • ubiquinol

- 2 electrons and 2 hydrogens

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7
Q

How many electrons and hydrogens does the semiquinone radical have?

A

1 electron and 1 hydrogen

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8
Q

Which carriers are mobile electron carrier? Which is immobile?

A
  • Mobile: ubiquinone and cytochrome c

- Immobile: iron-sulfur proteins

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9
Q

How many electrons does ubiquinone carry? How many does cytochrome c carry?

A
  • Ubiquinone: 2

- Cytochrome c: 1

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10
Q

What are iron-sulfur proteins always connected to?

A

Cysteine amino acids

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11
Q

What happens in complex I?

A
  • NADH transfers electrons
  • Electron passes through FMN and iron-sulfur centers
  • Electrons reduce ubiquinone to ubiquinol which travels to Complex III (addition of 2H+ from the matrix)
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12
Q

Which complex is linked to the TCA cycle? Through what?

A
  • Succinate dehydrogenase (succinate to fumarate)

- Transfers electrons from FADH2 to ubiquinone

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13
Q

What happens in complex II?

A
  • FADH2 transfers electrons
  • Electrons pass through FAD and iron-sulfur clusters
  • Electrons reduce ubiquinone to ubiquinol which travels to complex III
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14
Q

Which enzyme is involved in transferring electrons from FAD to ubiquinone? Which mechanism is it also located in?

A
  • Acyl-CoA dehydrogenase

- B-oxidation

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15
Q

Is NADH or FADH2 more present?

A

NADH, which comes from the cytoplasm following glycolysis

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16
Q

How many NADH molecules does B-oxidation give per cycle?

A

1 NADH

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17
Q

How many NADH molecules does glycolysis give per glucose?

A

2 NADH

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18
Q

How many NADH molecules does the synthesis of Acetyl-CoA from Pyruvate generate?

A

1 NADH

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19
Q

How many NADH molecules does the TCA cycle generate?

A

3 NADH

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20
Q

How many NADH molecules does AA oxidation to Pyruvate generate?

A

Numbers vary depending on the end-product of the degradation

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21
Q

How many protons are pumped into the intermembrane space in complex I?

A

4 protons

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22
Q

Are two electrons transferred at once to ubiquinone? Or one at a time?

A

One at a time (semiquinone –> ubiquinol)

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23
Q

What is complex I called?

A

NADH dehydrogenase

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24
Q

What is complex II called?

A

Succinate dehydrogenase

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25
Q

What is complex III called?

A

Cytochrome c reductase

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26
Q

What is complex IV called?

A

Cytochrome oxidase

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27
Q

How many protons are pumped into the intermembrane space in complex II?

A

None

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28
Q

How many protons are pumped into the intermembrane space in complex III?

A

4 protons

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29
Q

What happens in complex III?

A
  • Transfer of electrons and protons to cytochrome c in two stages
  • Formation of a semi-quinone, which becomes a ubiquinol (addition of two hydrogens from the matrix)
  • Two electrons are transferred to cytochrome c, which are carried to complex IV
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30
Q

How many ubiquinol molecules are needed to transfer 2 electrons to 2 cytochrome c molecules?

31
Q

How many electrons are pumped in complex IV?

32
Q

What happens in complex IV?

A
  • 4 electrons from cytochrome are transferred to iron-copper centers, cytochrome a, then to oxygen
  • Reduction of O2 to H2O (addition of 4 hydrogens from the matrix)
33
Q

In complex IV, how many protons are pumped per electron pair?

34
Q

How many molecules of H2O are created in complex IV?

35
Q

How can we observe the electron carriers of respirasomes?

A

Cryoelectron microscopy

36
Q

Which complex produces more electronchemical gradient?

A

Complex I (NADH)

37
Q

What is the electrochemical proton gradient created by? (3)

A

1) Active transport of protons
2) Release of protons into the intermembrane space
3) Chemical removal of protons from the matrix

38
Q

When is there an active transport of protons?

A
  • Complex I, Complex IV

- Protons are thrown out from the matrix into the intermembrane space

39
Q

When is there a release of protons into the intermembrane space?

A
  • Complex III

- Oxidation of ubiquinol

40
Q

When is there a chemical removal of protons from the matrix?

A
  • Reduction of Q (I, II, III) and oxygen (IV)

- Utilization of protons from the matrix side

41
Q

Describe the matrix and the intermembrane space.

A
  • Matrix: alkaline, negative

- Intermembrane space: acid, positive

42
Q

Which ATP synthase unit is membrane-bound? Which is bound to the matrix?

A
  • F0: membrane-bound

- F1: matrix

43
Q

Which ATP synthase unit catalyzes the hydrolysis of ATP?

44
Q

What is the function of the F0 subunit?

A
  • Transports protons down the gradient (outside to inside)

- Transfers energy to F1

45
Q

How many isoforms does ATP synthase contain?

46
Q

What connects the membrane to the matrix portion in the ATP synthase?

A

Gamma-shaft

47
Q

How many protons does a shift of the gamma shaft require? Where do the protons travel?

A
  • 3 H+

- Intermembrane (+) to the matrix (-)

48
Q

How many protons does P1 transport and phosphorylation of ADP require?

49
Q

How many protons are needed for each ATP produced?

50
Q

How many protons does NADH pump? How many ATPs does it produce?

A
  • 10 H+

- 2.5 ATP

51
Q

How many protons does FADH2 pump? How many ATPs does it produce?

A
  • 6 H+

- 1.5 ATP

52
Q

In which cells does the malate-aspartate shuttle occur in?

A

Most cells

53
Q

In which cells does the glycerol-3-phosphate shuttle occur in?

A

Skeletal muscle cells and neurons

54
Q

What is the function of mitochondrial shuttles

A

NADH from glycolysis can travel from the cytoplasm to the matrix by membrane shuttles

55
Q

How does the malate-aspartate shuttle function?

A

1) NADH converts oxaloacetate to malate (malate dehydrogenase)
2) Malate moves to the matrix through its transporter
3) Malate is converted to oxaloacetate, producing NADH (malate dehydrogenase)

56
Q

What does oxaloacetate from the malate-aspartate shuttle form in the matrix? Which enzyme is involved?

A
  • Oxaloacetate receives the amino group from glutamate and forms aspartate
  • Aspartate aminotransferase
57
Q

How does the glycerol-3-phosphate shuttle function?

A

1) NADH converts DHAP to glycerol-3-phosphate (glycerol-3-phosphate dehydrogenase)
2) Electrons are transferred to FAD+, which is reduced to FADH2
3) FADH2 transfers its electrons to ubiquinone, creating ubiquinol which is brought to complex III

58
Q

If NADH goes through glyceraldehyde-3-phosphate shuttle, it results in ___ ATPs

59
Q

If NADH goes through the malate aspartate shuttle, it results in ___ ATPs

60
Q

Does the oxidation of palmitate of glucose yield more ATP?

A
  • Glucose: 30 or 32

- Palmitate: 108

61
Q

How does the mass action ratio regulate oxidative phosphorylation?

A
  • ATP/(ADP)(Pi)

- Negatively correlated with ATP synthesis

62
Q

ATP is synthesized as fast as it is ______

63
Q

What does UCP1 stand for? What does it do?

A
  • Un-coupling protein 1

- Uncouples the proton movement across the membrane from ATP synthesis

64
Q

What is the function of UCP1?

A
  • Provides the path for protons to return to the matrix by BYPASSING ATP-synthase
  • Yields heat, but no energy
65
Q

Which mechanism explains how infants maintain their body temperature?

A
  • UCP1

- Brown adipose tissue fat

66
Q

Can brown adipose tissue fat be found in adults? Under what circumstances?

A
  • Rare

- The colder the environment, the more brown adipose tissue fat is used to produce heat

67
Q

What is the function of P450 oxygenases in the mitochondria? Which form of hydrogen does it utilize?

A
  • Catalyzes steroidogenesis

- Hydrogen from NADPH

68
Q

What is apoptosis?

A

Physiological-signalled cell death

69
Q

What is released when cellular stress tries to induce apoptosis? What does it bind to?

A
  • Cytochrome c (inner membrane and intermembrane space) is released
  • Binds to ATP and Apaf1
70
Q

What is formed when cytochrome c, ATP and Apaf-1 bind? What does that stimulate?

A
  • Apoptosome

- Causes dimerization of procaspase-9, creating active caspase-9 dimers

71
Q

What is the function of caspase-9? What are they also called?

A
  • Executioner proteins (involved in degrading macromolecules in the cell)
  • Will activate further caspases in the membrane, leading o the death of the cell
72
Q

What does Apaf1 stand for?

A

Apoptosis protease activating factor 1

73
Q

What is an apoptosome formed of?

A

Apaf 1 + cytochrome c + ATP

74
Q

What does abnormal mitochondrial function lead to?

A

Cancer or degenerative disease

2) Biochemistry II (23 decks)

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