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2nd yr- IBMS- Respiration and metabolism > Electron transport and oxidative phosphorylation > Flashcards

Electron transport and oxidative phosphorylation Flashcards

1
Q

What is oxidative phosphorylation?

A

Removal of electron from metabolic metabolic intermediates while simultaneously synthesising ATP from ADP

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2
Q

What is substrate level phosphorylation?

A

The formation of ATP via direct phosphorylation of ADP

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3
Q

Why does substrate level phosphorylation occur?

A

Occurs as some reactions have enough free energy to produce ATP directly and don’t require oxygen

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4
Q

Does substrate level phosphorylation require oxygen

A

NO

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5
Q

Name the reaction that generates all the energy we need for cellular processes?

A

Te hydrolysis of ATP

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6
Q

Other than providing energy what else does ATP act as?

A

Acts as a cofactor fro signal transduction reactions using a variety of kinases

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7
Q

What is the normal cellular ATP concentration maintains at

A

Maintained in the range of 1 to 10 mol/L

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8
Q

State the normal ratio of ATP/ADP

A

1000

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9
Q

What is the total quantity of ATP in an adult?

A

0.10 mol/L

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10
Q

Approx how much ATP do we require daily

A

100 to 150 mol/L of ATP are required daily

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11
Q

How many times a day is ATP recycled?

A

1000 to 1500 times per day

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12
Q

Where does the majority of respiration occur?

A

In the mitochondria

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13
Q

What is the mitochondria responsible for?

A

The generation of more than 95% of ATP

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14
Q

What does ATP stand for

A

adenosine triphosphate

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15
Q

Other than respiration what else is the mitochondria involved in?

A
  1. Intracellular signalling
    2 Intracellular calcium regulation
  2. Cellular differentiation and growth
  3. Cellular death pathways
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16
Q

Name the different structures of a mitochondrion

A 
1. Outer membrane 
2 Inner membrane 
3. Cristae 
4. Matrix 
5. Intermembrena space
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17
Q

What is the Matrox pf the mitochondria bound to?

A

Bound with the intermembrane membrane

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18
Q

How does oxidative phosphorylation begin?

A

Begins with the electron entering the respiratory chain

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19
Q

The electron needed fro oxidative phosphorylation to start come from where?

A

They arise from the action of dehydrogenase from catabolic pathways (E.g. glycolysis)

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20
Q

What happens when NADH is oxidised?

A

Electrons are released

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21
Q

State the chemical equation for the oxidation of NADH

A

2NADH -> 2NAD+ + 2H+ +4e-

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22
Q

Describe the electrons that form due to the oxidation of NADH

A

They are high in energy so if the oxidation of NADH was to occur in on step too much energy would be released all at once

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23
Q

How do we overcome the fact that the oxidation of NADH all at once would produce to many high energy electrons?

A

The high energy electron are passed sequentially from one complex to another to ensure that too much energy is not released at once

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24
Q

What do electrons react with to release energy?

A

Oxygen

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25
Q

State the chemical equation for the reaction of electrons with oxygen

A

4e- +4H+ + O2 -> 2H2O

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26
Q

Where is the electron transfer chain found?

A

At the inner mitochondrial membrane

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27
Q

What makes up the electron transfer chain?

A

4 complexes found on on the inner mitochondrial membrane

3 carriers

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28
Q

What is the function of the complexes found on the inner mitochondrial membrane

A
  1. Their job is to accept electrons to be able to pass energy though the chain
  2. They use this energy to pump hydrogens into the inter-membrane space
29
Q

What happens at complex I?

A

NaDH and FADH2 transfer electrons onto complex I

Energy obtained fro themeless electrons is used to pump out 4 electrons into the inter-membrane space

30
Q

What does complex II do?

A

It accepts electrons from NADH and FADH2

The energy from these electrons is used to supercharge complex III

31
Q

What happens at complex III

A

Complex III is super charged by complex II and releases 4 protons into the inter-membrane space

32
Q

What does complex IIII do?

A

It releases 2 protons into the inter-membrane space

33
Q

How are the elecron carriers of the electron transfer chain organised?

A

Organised into membranes

they are embedded supramolecular complexes that can be physically separated

34
Q

Name the electron carriers present in the electron transfer chain

A
  1. Universal carriers NADH and FADH2
  2. Ubiquinone
  3. Cytochrome C
35
Q

Name electron carrier 1

A

Flavin mononucleotide FMN

36
Q

What does FMN do?

A

It oxidises NADH to NAD+ becoming reduced by accepting electron

37
Q

Name complex I

A

NADH-Q oxireductase/ dehydrogenase

38
Q

Describe the structure of FMN

A

It has a similar structure to FAD but just has a different R group

39
Q

When does FMN bind to protons

A

FMN bonds to proton when they are reduced

40
Q

How can FMN accept electrons

A

Can accept electrons via the semi-quinone intermediate

41
Q

Give the chemical formula for the reduced forms of FMN

A

FMNH2

42
Q

How is the energy from electrons harnessed in complex I

A

Harnessed through a series of Fe-S complexes

43
Q

How does sulphur exist in the electron transport change

A

Exists in the amino acid cystine

44
Q

Describe a Fe-S complex with only one iron atom

A

A single iron atom is tetrahedrally coordinated with 4 cystine-SH groups

45
Q

Describe the journey of electrons starting at FMNH2 in the complex I

A

Electrons from FMNH2 cascade down a series of Fe-S complexes via direct transfer

46
Q

Name electron carrier 3

A

Co enzyme Q

47
Q

After the electrons have gone through the Fe-S cascade what needs to be done and how ?

A

The electrons need to be carried by co enzyme Q

48
Q

Where is ubiquinone found?

A

In the inter membrane space of the mitochondria

49
Q

Describe the structure of ubiquinone

A

Has a large hyrdrocarbon change attached to a benzene ring

It is uncharged and fully oxidised

50
Q

What is another name for co enzyme Q?

A

ubiquinone

51
Q

Wha is co enzyme Q

A

It is a hydrophobic quinone that diffuses rapidly within the inter mitochondrial membrane

52
Q

What forms can ubiquinone be found in?

A

1, Semiqunione radical which is a semi reduced form

2, Ubiquinol (QH2) which is fully reduced

53
Q

Summarise what happens in complex I

A

Complex I catalyses 2 simultaneous couples processes;

  1. The exorgonic transfer of hydride ion from NADH and a proton from the matrix (NADH + H+ +Q -> NAD+ +QH2)
  2. The exergonic transfer of 4 protons from the matrix into the inter membrane space
54
Q

What is complex II called?

A

Succinate dehydrogenase

55
Q

Describe Complex II

A

It is a membrane bound enzyme in the citric acid cycle

56
Q

What does complex II contain?

A
  1. 2 Fe-2S centres
  2. A bound FAD
  3. Binding sire for the substrate succinate
57
Q

In complex II how far do electrons have to travel from the succinate binding site to Q?

A

40A

58
Q

Name Complex III

A

Cytochrome bc1

59
Q

Wha does cytochrome bc do?

A

It couples the transfer of electrons from ubiquinol to cytochrome c with the transport of H+ from the matrix to the inner inter membrane space

60
Q

State the overall chemical equation for the Q cycle

A

QH2 + 2cyrochrome C +2H -> Q + 2reduced cytochrome c + 4H+

61
Q

What is complex 4 made up of?

A

2 heme groups and 2 copper centres

62
Q

What is complex IV called?

A

Cytochrome c Oxidase

63
Q

What happens at complex IV?

A
  1. The first copper centre accepts electrons from reduces cytochrome c and reduces he second copper centre
  2. A second reduced cytochrome c reduces the iron in
    the second heme
  3. This iron centre binds with oxygen. to form peroxide from the transfer of 2 electrons
  4. The bound oxygen bridges the iron and copper
  5. The third cytochrome c dumps ad electron which cleavers the O-O bond and takes a proton
  6. A 4th cytochrome c dumps an electron to facilitate the reduction of iron
  7. 2 protons are taken up allowing 2H2Os to be released
64
Q

Summarise the electron transport chain

A

It is basically harnessing high energy electrons and then pushing them onto oxygen

65
Q

Which molecule carries out the synthesis of ATP?

A

ATP synthase

66
Q

Name the hypothesis that explains how ATP synthase makes ATP

A

chemiosmotic hypothesis

67
Q

Talk through the chemiosmotic hypothesis

A
  1. Protons are pumped into the inte rmembreane space making it positively charged
  2. This creates an electric field with the mitochondrial matrix being negatively charged
  3. This gradient gives us the proton motive force
68
Q

State the equation for the proton motive force

A

Proton motion force=

Chemical gradient + Charge gradient

2nd yr- IBMS- Respiration and metabolism (3 decks)

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