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Biochem midterm 2 > ETC and Oxidative Phosphorylation > Flashcards

ETC and Oxidative Phosphorylation Flashcards

1
Q

What generates the energy in the proton gradient?

A

Transferring electrons from NADH and FADH2 to oxygen

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2
Q

What is the free energy from the proton gradient used for?

A

Oxidative phosphorylation

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3
Q

Which complex in the ETC does the oxidation step occur?

A

In complex IV

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4
Q

In which complex does the phosphorylation of ADP to ATP occur?

A

In complex V

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5
Q

Do electrons get transferred in Complex V?

A

No its where ATP is synthesized

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6
Q

What is the final electron acceptor?

A

Oxygen is the final acceptor, it is reduced to H2O

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7
Q

What is the electron transfer potential?

A

It is what keeps the electrons flowing in forward direction

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8
Q

What is the flow of the 2 electrons through complex I

A

NADH2 - FMN (FMNH2) - Fe-S x3 - Q (QH2)

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9
Q

How many protons get pumped as a result of electron flow through complex I

A

4 protons get pumped

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10
Q

What are the oxidized and reduced versions of flavin mononucleotide?

A

FMN and FMNH2

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11
Q

What are the 3 states that Q can exist in?

A

Oxidized state - Q ; semiquinon -QH ; fully reduced - QH2

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12
Q

What is the final result of the 6 protons in complex I?

A

2 reduce Q to QH2 and 4 get pumped out into intermembrane space

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13
Q

From complex I, QH2 goes where?

A

Straight to complex III

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14
Q

Where does FADH2 carry its electrons to?

A

It goes straight to complex II

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15
Q

Do any protons get pumped when FADH2 reduces Q to QH2?

A

No, it isjust increasing QH2 content in the Q pool

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16
Q

The ETC is made up of a chain of electron carriers with _ redox potential

A

increasing

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17
Q

How many electrons can cytochrome c accept at a time?

A

One, eventhough QH2 has 2 to give.

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18
Q

What are the 3 types of hemes in complex III?

A

2 b-type: Heme bL and heme bH, 1 c-type Heme c1

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19
Q

What happens in first half of q cycle?

A

QH2 is oxidized, 1 electron goes to cytochrome c and one electron goes to reduce a Q into semiquinone state. 2 Protons pumped into intermembrans space

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20
Q

What happens in second half of q cycle?

A

Another QH2 is oxidized, 1 to cytochrome c and another to the semiquinone Q to fully reduce it to QH2. 2 more protons get pumped into intermembrane space

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21
Q

What is the net QH2 metabolism of the q cycle?

A

1, because one is generated

22
Q

What are the 4 electron accepting molecules in complex IV?

A

2 hemes - Heme a and Heme a3. 2 copper centers - copper a and copper b

23
Q

What is the flow of electron in complex IV?

A

From cytochrome c to copper a, then transfers to heme a then finally to heme a3/copper b site

24
Q

What site in complex IV reduces oxygen to H2O?

A

heme a3 / copper b site

25
How do electrons flow to reduce molecular oxygen?
4 cytochromes c's bring 4 electrons to make 2 molecules of H2O. The first 2 cleave the peroxide bridge and the next to protonate the OH groups on the Fe and Cu releasing the water
26
What is the energy released from the reduction of water used to do?
Energy released from 2 reduced molecules of water causes 4 protons pumped into intermembrane space
27
How many NADH or FADH2 is needed to release one water molecule?
2 to release water
28
1 NADH contributes to how many protons being pumped?
10 - 4 in complex I, 0 in complex II, 4 in complex III, 2 in complex IV.
29
1 FADH2 contributes to how man protons being pumped?
6 - 0 in complex I, 0 in complex II, 4 in complex III and 2 in Complex IV
30
What does super oxide dismutase do?
It defends against reactive oxygen species. It can exist in an oxidized or reduced state.
31
What does catalase do?
Catalyzes the reduction of hydrogren peroxide.
32
What does the energy stuck in the intermembrane space do?
Drives ATP synthesis
33
3 postulates for chemiosmotic theory
1. Intact inner mitochondrial membrane, 2. e- transport through ETC creates proton gradien 3. ATP synthase catalyzes the phosphorylation of ADP driven by the movement of H+ across the inner membrane into the matrix
34
What are the 2 components of proton motive force?
Chemical pH gradient and charge gradient
35
What are the 2 assemblies of complex V?
Complex V is made of F0 which sits in the membrane and F1 that protrudes into the mitochondrial matrix.
36
What is the stoichiometry of the F1 subunit?
3-alpha 3-beta , gamma, delta, epsilon
37
In complex V which subunit rotates and which subunit is stationary?
F0 rotates and F1 is stationary
38
What is are the 3 beta subunit conformations?
L-loosely binds to ADP and Pi, Tight- catalyzed the formation ATP, O-open to release ATP and allow another ADP and Pi to enter
39
How does the beta-subunit change conformation?
The rotation of the gamma subunit
40
What part of the membrane is ATP synthases rotating structure located?
Inner mitochondrial membrane
41
Which subunit in complex V contains the catalytic center that synthesizes ATP?
F1 subunit
42
What are the two channels of the alpha subunit?
Cytoplasmic half-channel that leads to the intermembrane space and the matrix half channel that leads to the matrix.
43
How do protons enter complex V?
Through the two half channels in the alpha subunit.
44
What is the environment inside the alpha subunit half-channels?
Hydrophilic aqueous environment
45
What are the two environments that the c subunit interacts with?
Hydorphilic half channels and hydrophobic membrane
46
What causes the rotation of the c subunits?
The transfer of protons down from intermembrane space and into the mitochondrial matrix
47
How does the rotation of the c subunits drive ATP synthesis?
Rotation of the c subunits rotates the attached gamma subunit and changes the conformation of the beta subunits
48
1 full rotation of the c subunits makes how many ATP?
3 ATP
49
How do you get ADP into the matrix and ATP out of the matrix?
ATP-ADP translocase protein, this protein makes up about 15% of the inner mitochondrial membrane
50
How do you regenerate the membrane potential after pumping out the extra negative charge with ATP?
Pump an extra proton
51
How does NADH in the cytoplasm get oxidized if it cant pass through the inner membrane?
It passes its electrons to G3P shuttle and the shuttle passes the electrons to FADH2
52
NADH from the cytoplasm contributes to how many protons getting pumped?
Protons from NADH in the cytoplasm go to FADH2 and enter ETC

Biochem midterm 2 (6 decks)

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