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Biochem (2016) > Electron transport chain > Flashcards

Electron transport chain Flashcards

1
Q

What are the electron carriers involved in the ETC?

A

1) Coenzyme Q (ubiquinone)
2) Cytochromes
3) Fe-S proteins

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2
Q

What is a distinguishing characteristic of coenzyme Q?

A

Long lipid soluble aliphatic tail

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3
Q

Can ubiquinone accept or donate electrons?

A

Both

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4
Q

Which cytochrome is not an integral membrane protein?

A

Cytochrome c

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5
Q

What causes cytochromes to be different?

A
  • Different amino acid sequences

- Different binding to iron-containing hemes

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6
Q

What type of protein is cytochrome c?

A

Peripheral membrane protein

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7
Q

What does cytochrome c bind and how?

A

Binds heme C covalently via cys residues

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8
Q

What is standard reduction potential?

A

A measure of the free energy of the electron

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9
Q

Why are the electron carriers arranged in the way they are?

A

So that a given carrier can accept electrons from one carrier only and pass them to one carrier only

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10
Q

Carriers with high ___ reduction potentials pass electrons to carriers with high ____ reduction potentials

A
  • Negative

- Positive

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11
Q

What is the net reaction that occurs are complex 1?

A

NADH + H+ + UQ -> NAD+ + UQH2

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12
Q

What happens to UQH2 in complex 1?

A

It diffuses through the membrane to complex 3

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13
Q

How many hydrogens are pumped across the membrane in complex 1?

A

4

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14
Q

What is the name of complex 1?

A

NADH dehydrogenase

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15
Q

What is the name of complex 2?

A

Succinate dehydrogenase

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16
Q

What is the only membrane-bound enzyme of the TCA cycle?

A

Complex 2/succinate dehydrogenase

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17
Q

What is the net reaction that occurs in complex 2?

A

FADH2 + UQ -> FAD + UQH2

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18
Q

What is the name of complex 3?

A

UQ-cyt c oxidoreductase

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19
Q

What happens to cytochrome c in complex 3?

A

It dissociates from complex 3 and carries 1 electron at a time to complex 4

20
Q

What is the net reaction that occurs in complex 3?

A

UQH2 + 2Cyt c-Fe3+ -> UQ + 2Cyt c-Fe2+

21
Q

How many hydrogens are pumped across the membrane by complex 3?

22
Q

What is the name of complex 4?

A

Cytochrome oxidase

23
Q

What is the net reaction that occurs at complex 4?

A

2Cyt c-Fe2+ + 1/2O2 + 2H+ -> 2 Cyt c-Fe3+ + H2O

24
Q

What do 2 electrons pass through in complex 4 and where do these electrons come from?

A
  • Pass from cyt c to 1/2 O2

- Come from 1 NADH

25
Q

How many hydrogens are pumped across the membrane in complex 4?

26
Q

How is energy stored during electron transport?

A

In the form of a proton concentration gradient

27
Q

Electrons in ____ have high G

28
Q

Electrons in _____ have low G

29
Q

How much free energy is needed to make 1 ATP from ADP and Pi?

A

30.5 kJ/mol

30
Q

How many ATPs are formed when electrons are transferred from NADH to O2?

31
Q

How many ATPs are formed from succinate oxidation?

32
Q

How is free energy of electron flow converted into ATP synthesis?

A

During transport of 2 e- down the ETC from NADH, complexes 1, 3, and 4 transport 10 H+ from the matrix into the space between the inner and outer membranes, using the free energy

33
Q

Where is OH- found?

A

In the matrix

34
Q

Where is H+ found?

A

In the space

35
Q

How many hydrogens are moved for every 2 electrons passing down the chain from NADH?

A
  • 4 are pumped by complex 1
  • 4 are pumped by complex 3
  • 2 are pumped by complex 4
36
Q

How many hydrogens are moved for every 2 electrons passing down the chain from FADH2?

A
  • 4 are pumped by complex 3

- 2 are pumped by complex 4

37
Q

How is the H+ gradient coupled to ATP synthesis?

A

FoF1 ATP synthase

38
Q

What is generated as H+ flows through Fo?

A

A torque that is transmitted to F1 via the gamma-shaft

39
Q

Do Fo and F1 subunits rotate in the same or opposite directions and what is this rotation energy used for?

A
  • Opposite

- To release ATP from its binding site

40
Q

What is electron transport tightly coupled to?

A

Oxidative phosphorylation

41
Q

What regulates oxidative phosphorylation?

A

The supply of ADP and phosphate

42
Q

What is the function of the enzyme ATP/ADP translocase?

A

To move ATP into the cytoplasm and ADP into the mitochondrion

43
Q

How many ATPs are produced from glycolysis and by what processes?

A
  • 5 from 2 NADH + H+ in the ETC

- 2 from substrate level phosphorylation

44
Q

How many ATPs are produced from the conversion of pyruvate to acetyl CoA and where?

A

5 from 2 NADH + H+ in the ETC

45
Q

How many ATPs are produced from the citric acid cycle and by what processes?

A
  • 2 from 2 GTP from substrate level phosphorylation
  • 3 from 2 FADH2 in the ETC
  • 15 from 6 NADH + H+ in the ETC

Biochem (2016) (8 decks)

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