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2) Biochemistry II > Oxidative Phosphorylation > Flashcards

Oxidative Phosphorylation Flashcards

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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
What is complex III called?
Cytochrome c reductase
26
What is complex IV called?
Cytochrome oxidase
27
How many protons are pumped into the intermembrane space in complex II?
None
28
How many protons are pumped into the intermembrane space in complex III?
4 protons
29
What happens in complex III?
- 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
30
How many ubiquinol molecules are needed to transfer 2 electrons to 2 cytochrome c molecules?
2
31
How many electrons are pumped in complex IV?
4 protons
32
What happens in complex IV?
- 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
In complex IV, how many protons are pumped per electron pair?
2 protons
34
How many molecules of H2O are created in complex IV?
2
35
How can we observe the electron carriers of respirasomes?
Cryoelectron microscopy
36
Which complex produces more electronchemical gradient?
Complex I (NADH)
37
What is the electrochemical proton gradient created by? (3)
1) Active transport of protons 2) Release of protons into the intermembrane space 3) Chemical removal of protons from the matrix
38
When is there an active transport of protons?
- Complex I, Complex IV | - Protons are thrown out from the matrix into the intermembrane space
39
When is there a release of protons into the intermembrane space?
- Complex III | - Oxidation of ubiquinol
40
When is there a chemical removal of protons from the matrix?
- Reduction of Q (I, II, III) and oxygen (IV) | - Utilization of protons from the matrix side
41
Describe the matrix and the intermembrane space.
- Matrix: alkaline, negative | - Intermembrane space: acid, positive
42
Which ATP synthase unit is membrane-bound? Which is bound to the matrix?
- F0: membrane-bound | - F1: matrix
43
Which ATP synthase unit catalyzes the hydrolysis of ATP?
F1
44
What is the function of the F0 subunit?
- Transports protons down the gradient (outside to inside) | - Transfers energy to F1
45
How many isoforms does ATP synthase contain?
3(trimer)
46
What connects the membrane to the matrix portion in the ATP synthase?
Gamma-shaft
47
How many protons does a shift of the gamma shaft require? Where do the protons travel?
- 3 H+ | - Intermembrane (+) to the matrix (-)
48
How many protons does P1 transport and phosphorylation of ADP require?
1 H+
49
How many protons are needed for each ATP produced?
4 H+
50
How many protons does NADH pump? How many ATPs does it produce?
- 10 H+ | - 2.5 ATP
51
How many protons does FADH2 pump? How many ATPs does it produce?
- 6 H+ | - 1.5 ATP
52
In which cells does the malate-aspartate shuttle occur in?
Most cells
53
In which cells does the glycerol-3-phosphate shuttle occur in?
Skeletal muscle cells and neurons
54
What is the function of mitochondrial shuttles
NADH from glycolysis can travel from the cytoplasm to the matrix by membrane shuttles
55
How does the malate-aspartate shuttle function?
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
What does oxaloacetate from the malate-aspartate shuttle form in the matrix? Which enzyme is involved?
- Oxaloacetate receives the amino group from glutamate and forms aspartate - Aspartate aminotransferase
57
How does the glycerol-3-phosphate shuttle function?
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
If NADH goes through glyceraldehyde-3-phosphate shuttle, it results in ___ ATPs
3
59
If NADH goes through the malate aspartate shuttle, it results in ___ ATPs
5
60
Does the oxidation of palmitate of glucose yield more ATP?
- Glucose: 30 or 32 | - Palmitate: 108
61
How does the mass action ratio regulate oxidative phosphorylation?
- ATP/(ADP)(Pi) | - Negatively correlated with ATP synthesis
62
ATP is synthesized as fast as it is ______
utilized
63
What does UCP1 stand for? What does it do?
- Un-coupling protein 1 | - Uncouples the proton movement across the membrane from ATP synthesis
64
What is the function of UCP1?
- Provides the path for protons to return to the matrix by BYPASSING ATP-synthase - Yields heat, but no energy
65
Which mechanism explains how infants maintain their body temperature?
- UCP1 | - Brown adipose tissue fat
66
Can brown adipose tissue fat be found in adults? Under what circumstances?
- Rare | - The colder the environment, the more brown adipose tissue fat is used to produce heat
67
What is the function of P450 oxygenases in the mitochondria? Which form of hydrogen does it utilize?
- Catalyzes steroidogenesis | - Hydrogen from NADPH
68
What is apoptosis?
Physiological-signalled cell death
69
What is released when cellular stress tries to induce apoptosis? What does it bind to?
- Cytochrome c (inner membrane and intermembrane space) is released - Binds to ATP and Apaf1
70
What is formed when cytochrome c, ATP and Apaf-1 bind? What does that stimulate?
- Apoptosome | - Causes dimerization of procaspase-9, creating active caspase-9 dimers
71
What is the function of caspase-9? What are they also called?
- Executioner proteins (involved in degrading macromolecules in the cell) - Will activate further caspases in the membrane, leading o the death of the cell
72
What does Apaf1 stand for?
Apoptosis protease activating factor 1
73
What is an apoptosome formed of?
Apaf 1 + cytochrome c + ATP
74
What does abnormal mitochondrial function lead to?
Cancer or degenerative disease

2) Biochemistry II (23 decks)

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