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IBMS SR > electron transport and oxidative phosphorylation > Flashcards

electron transport and oxidative phosphorylation Flashcards

1
Q

what does oxidative phosphorylation mean

A

the removal of electrons from metabolic intermediates and the synthesis of ATP from ADP

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2
Q

what processes can ATP help with

A

cofactor for signal transduction reaction using a variety of kinases

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3
Q

what is the cellular ATP concentration usually

A

1-10mmol/L

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4
Q

what is the total quantify of ATP in an adult

A

0.1mol/L

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5
Q

how many mols/l of atp is required daily

A

100 to 150 mol/L

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6
Q

how many times is an ATP molecule recycled

A

1000-1500 times per day

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7
Q

how much percentage of atp does the mitochindria make

A

more than 95% of ATP to support aerobic respiration

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8
Q

what processes is the mitochondria also involved in

A

intracellular signalling
intracellular calcium regulation
cellular differentiation and growth and cellular death pathways

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9
Q

what is located in the mitochondrial matrix

A

an independent mitochondrial genome

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10
Q

describe the mitochondria

A

the outer membrane- contains porins which allows for diffusion of ATP, ADP,CA,PHOSPHATE into the intermembrane space
the inner membrane- binds the matrix which is folded into cristae to increase the SA

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11
Q

how does OP begin

A

by electrons entering the respiratory chain

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12
Q

where do the electrons which are used in OP come from

A

the action of dehydrogenase from catabolic pathways- attached to NAD AND FAD

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13
Q

what is the equation for the breakdown of NADH

A

2NADH—> 2NAD+2H+ 4e-

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14
Q

what happens to the electrons that are released from NAD

A

high energy electrons are passed from one complex to another down an electron chain

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15
Q

what are the complexes arranged in

A

increasing potential and increasing electron affinity

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16
Q

how many complexes are there in the ETC

A

4

complex 1,2,3,4

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17
Q

what happens to the electrons when they reach complex 4

A

react with hydrogen and oxygen to form water

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18
Q

what happens as electrons move down the ETC

A

they release energy which allows hydrogen ions to be actively transported into the intermembrane space

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19
Q

how are the electron transporters arranged

A

organised into the membrane and embedded supramolecular complexes

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20
Q

where does NADH drop electrons in the ETC

A

complex 1

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21
Q

where does FADH drop electrons in the ETC

A

complex 2

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22
Q

what are the three electron carriers

A

ubiquinone
cytochrome c reductase
cytochrome c

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23
Q

what is the first electron carrier

A

flavin mononucleotide

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24
Q

what does flavin mononucleotide do

A

it oxidises NADH to NAD and becomes reduced by accepting electrons

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25
Q

what is the name of complex 1

A

NADH-Q oxidoreductase

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26
Q

what is the pathway of FMN becoming reduced

A 
flavin mononucleotide 
semiquinone intermediate 
flavin mononucleotide (reduced)
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27
Q

what needs to happen to the electrons for the energy to be released

A

passed down a number of iron sulphate complexes

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28
Q

how is iron bound to sulphur

A

a single iron atom is tetrahedrally coordinated with 4 SH–Cys groups

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29
Q

what happens to the iron molecules in this reaction

A

they can switch between fe2+ and fe3+

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30
Q

which amino acid is Sulphur found in

A

cysteine

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31
Q

how does the electron transfer oxidation and reduction occur

A

by direct transfer

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32
Q

what is the third electron carrier

A

co enzyme Q/ubiquinone

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33
Q

what happens to the electrons after they are carried by the FE-S complex

A

they are carried by ubiquinone which can diffuse rapidly within the inter mitochondria membrane

34
Q

describe ubiquinone

A

it is a hydrophobic quinone which can diffuse across the membrane

35
Q

what is the pathway of ubiquinone reduction

A

ubiquinone(full oxidised)
semiquinone radical
ubiquinol ( fully reduced)

36
Q

what are the two functions in complex 1

A
  1. the transfer to ubiquinone of a hydride ion from NADH and a proton from the matrix
  2. pumps four protons into the IMS
37
Q

what is complex two called

A

succinate dehydrogenase-

38
Q

what is different about succinate dehydrogenase

A

the only membrane bound enzyme in the citric acid cycle

39
Q

what is contained into complex 2

A

three 2[Fe-S] centres
a bound FAD
and a binding site for the substrate succinate

40
Q

what is the electron pathway in complex 2

A 
succinate binding site to FAD 
FE-S
FE-S
FE-S 
Q
41
Q

what is the name of complex 3

A

cytochrome bc1

42
Q

what occurs in cytochrome bc1

A

couples the transfer of electrons from ubiquinol to cytochrome c with the transport of H+ from the IMS

43
Q

what is the coupling of the electron transfer from ubiquinol and the transport of H+ called

A

the Q cycle

44
Q

what is complex 4 called

A

cytochrome c oxidase

45
Q

what is contained in complex 4

A

2 heme groups and 2 copper centres

46
Q

what does the copper centre do in complex 4

A

accepts electrons from reduced cytochrome c and reduces the second copper centre

47
Q

what is the pathway of the electron in complex 4

A
  1. first cooper centre accepts electrons from reduced cytochrome c and reduces the second copper centre
  2. electron transfer to Fe in heme a2
  3. both copper centre and iron in heme is in a reduced state
  4. the iron centre binds with oxygen and the bound oxygen forms peroxide from the transfer of 2 electrons
  5. the oxygen bridges the fe and cu- formation of the peroxide bridge
  6. the third cytochrome c dumps electron and cleaves the O-O bond and takes a proton
  7. the fourth cytochrome c dumps electrons and reduces the ferryl group
  8. an uptake of 2 protons allows for the release of 2H20
48
Q

how is ATP produced in ATP synthase

A

chemiosmotic hypotheses

49
Q

what enzyme synthesises ATP

A

ATP synthase

50
Q

how does the chemiosmotic hypothesis work

A

as protons are pumped into the membrane space it is now positively charged- results in an electric field with the mitochondrial matrix being negatively charged

51
Q

how is the proton motive force calculated

A

chemical gradient + charge gradient

52
Q

what is the symbol for proton motive force

A

delta p

53
Q

what is the symbol for chemical gradient

A

delta pH

54
Q

what is the symbol for charge gradient

A

delta psi

55
Q

describe ATP synthase

A

two functional domains

f0 and f1

56
Q

describe the f0 domain

A

is embedded into the inner mitochondrial membrane and has a proton pore through which protons leak
a single unit binds to the outside

57
Q

what are the subunits of ATP synthase

A

F1
F0
axle
stator

58
Q

describe the F1 matrix

A

it extends into the mitochondrial matrix and contains the catalytic activity of the synthase of ATP
ADP+Pi—> ATP+H20

59
Q

what is the free energy in the reaction of ATP synthase

A

free energy change close to zero

and is readily reversible

60
Q

how many units does F1 contain

A 
5 units 
3x alpha  
3x beta 
delta
epsilon 
and upsilon
61
Q

what subunit connects the F1 unit to the F0 unit

A

epsilon and an external column called a stator

62
Q

what does the F1 region do

A

binds the ADP +Pi
catalyse the reaction of ATP
release the ATP

63
Q

what does the F1 region look like

A

3 alpha and 3 beta hexamer ring

64
Q

which structure rotates in the F1

A

the gamma structure rotates only and not the alpha and beta

65
Q

what is contained in the 3 alpha in the hexamer ring

A

contain bound ATP but does not participate in the reaction

66
Q

what three states is beta found in the F1 structure

A

open
loose
tense

67
Q

where is ATP released out of from the beta subunits of F1

A

only in the OPEN STATE

68
Q

what happens in the tense state of the B subunit of F1

A

the ADP+Pi are close enough to produce ATP

69
Q

what is the evidence of rotational catalysis

A

genetically engineered f1 allowed for the attachment of ATP synthase to a Ni complex
biotin was covalently attached to C on F0
and the actin was labelled with a fluorescent probe and found to move when ATP was introduced as a substate

70
Q

how are the electrons from NADH transported into the mitochondria

A

via the G3P shuttle

71
Q

describe the G3P phosphate shuttle

A
  1. a pair of electrons are transferred from NADH to dihydroxyacetone phosphate
  2. forming glycerol 3 phosphate via the enzymatic catalysis using cytoplasmic G3P dehydrogenase
  3. G3P is deoxidised to DHAP via G3P dehydrogenase
  4. electron pair is transferred to FAD forming FADH2
  5. the reduced flavin transfers the electrons onto Q cycle
72
Q

what electron shuttle occurs in the liver and heart

A

the malate aspartate shuttle

73
Q

describe the malate aspartate shuttle

A
  1. electrons are transferred from NADH to oxaloacetate producing malate
  2. malate then moves through the membrane and deoxidised by NAD+ via malate dehydrogenase
  3. glutamine reacts with oxaloacetate forming aspartate
  4. aspartate then moves out via the exit shuttle
74
Q

how does ATP and ADP move into the inner mitochondrial membrane

A

ATP-ADP translocase

75
Q

how many transporters are coded into the human genome

A

40

76
Q

give some examples of the transporters coded by the human genome

A 
ATP-ADP translocase 
dicarboxylate carrier 
tricarboxylate carrier 
pyruvate carrier 
phosphate carrier
77
Q

what are other ways ATP can be produced

A

by uncoupled mitochondria- a type of brown fat adipose tissue generates heat
contained in this is an unique uncoupling protein which bypasses the f0 and f1 complex so the energy of oxidation is dissipated as heat

78
Q

what does 2,4 Dintrophenol do

A

it uncouples the electron transport by directly transporting proteins across the mitochondrial membrane- ATP not synthesised

79
Q

what can 2,4 Dinitrophenol do

A

photographic chemical
a fertiliser
used in dyes and explosives
was used for weight loss in 1933 but banned in 1938

80
Q

what molecules inhibit the electron transport chain

A

rotenone
antimycin A
cyanide and carbon monoxide

IBMS SR (38 decks)

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