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biochemistry > electron transport chain > Flashcards

electron transport chain Flashcards

1
Q

where is ETC located?

A

in the inner mitochndrial membrane

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2
Q

what is the final acceptor in the electron transport chain?

A

o2

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3
Q

where does O2 recieve its electron from in the electron transport chain?

A

from NADH and FADH2

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4
Q

What are FADH2 and NADH converted to after they are oxidized?

A

to NAD+ and FAD

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5
Q

what is the function/purpose of the electron transport chain?

A

to oxidize NADH and FADH2 to be recycled, and to create an electron gradient across the inner mitochondrial membrane to drive phosphorylation of ADP to ATP

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6
Q

what is the purpose of NADH and FADH2 in the ETC cycle?

A

to release the stored energy from NADH and FADH2 for ATP

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7
Q

why do we need an electron transport chain?

A

we need it to generate ADP to ATP from the energy rich molecules NADH and FADH2

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8
Q

where is PDH located?

A

in the mitochondrial matrix

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9
Q

where are protons trapped?

A

in the space between the inner and outer mitochondria

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10
Q

what is happening in the electron transport cycle?

A

electrons are transported, molecules are being oxidized and phosphorylated

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11
Q

true or false. is there a net loss in electrons?

A

no molecules are just being transported from one complex to the other

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12
Q

why are the charged molecules in the electron transport chain trapped in the middle of the membrane?

A

because the inner mitochondrial memebrane is impermeable meaning that it is slective on what it allows in

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13
Q

since there are alot of protons in the intermembranous space than in the matrix, what will be driven to produce ATP?

A

ATP synthetase

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14
Q

what are NADH and FADH2 considered when going through the complexes in the electron transport chain?

A

substrates

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15
Q

how many stationary complexs do we have?

A

5

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16
Q

what is the prosthetic group that it formed using NADH to NAD+ in complex 1?

A

FMN to FMNH2

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17
Q

in complex 2 what are the molecules that are present?

A

succinate, fumarate, FADH2 to FAD+

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18
Q

what is the first carrier protein between complex 1 and 2 going to 3?

A

CoQ to CoQH2(quinolone)

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19
Q

what is the carrier protein in complex 3 and what is being oxidized?

A

Cytobc1 and Fe2+to Fe3+

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20
Q

what is the carrier that links complex 3 and 4 together?

A

cytoC

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21
Q

what carrier protein is located in complex 4?

A

cytoa + a3

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22
Q

it is a carrier protein that is lipopholic in nature and mobiltiy to move around, which carrier protein is this?

A

CoQ

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23
Q

what are the mobile/ nonstationary carriers between the complexes?

A

CoQ( complex 123) and CytoC (cpmplex 3 and 4)

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24
Q

what complex is FADH2 found?

A

in complex 2

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25
Q

where is NADH located?

A

complex 1

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26
Q

what is the enzyme utilized in complex 1?

A

NADH dehydrogenase

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27
Q

what is the enzyme utilized in complex 2?

A

succinate dehydrogenase

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28
Q

what enzyme isutilized in complex 3?

A

cytochrome reductase

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29
Q

what enzyme is present in complex 4?

A

cytochrome oxidase

30
Q

what are the organic molecules (prosthetic groups) that are needed in complex 1 and 2?

A

FMN and FAD ( Riboflavin)

31
Q

will the complex be able to function without there prosthetic groups?

A

no because they are required for funtion of the complexes

32
Q

what is the prosthetic group in complex 3?

A

heme group ( Fe3+)

33
Q

what is the prosthetic group in complex 4?

A

CU2+ and Fe3+

34
Q

what does compex 1,2, and 3 have that complex 4 doesnt?

A

iron-sulfur proteins

35
Q

when electrons are passed through each complex, what is being released?

A

protons are relased

36
Q

where does NADH come from?

A

malate dehydrogenase (MDH), alpha keto glutarate dehydrogenase, isocitrate dehydrogenase, pyruvate dehydrogenase (PDH), and fatty acid beta oxidation and cystolic sources of glycolysis

37
Q

where does FADH2 originate from?

A

succinate dehydrogenase, or the associated CoQ gets them from the glycerol phosphate shuttle or fatty acid beta oxidation

38
Q

what is the stalk of the atp synthase made of?

A

F naut is the proton port and F1 is the enzyme protion

39
Q

where are the protons traveling to?

A

the matrix

40
Q

what inhibits NADH dehydrogenase in complex 1?

A

reotenone, piericidin A (bacteial antibiotic) barbiturate amytal

41
Q

what inhibits cytochrome b of cytochrome reductase in complex 3?

A

antimycin A (an antibiotic)

42
Q

what inhibits cytochrome oxidase(complex 4)?

A

CO, azide, Hydrogen sulphide (H2S) and cyanide(CN-)

43
Q

what inhibits ATP synthetase?

A

oligomycin (a streptomyces antibiotic)

44
Q

when inhibitors are present what happens to Atp synthesis the ETC and O2 consumption?

A

they decrease

45
Q

what is adenine nucleotide translocase?

A

a unidirectional exchange of ATP to ADP (antiport)

46
Q

is inorganic phosphate and H+ , which are electroneutral, a symport or antiport?

A

symport

47
Q

what are two toxic molecules that inhibit ADP/ATP transport?

A

atractyloside: toxic glycoside binds the outward facing(intramembranous space) portion of the adenine nucleotide transport and BONGKREKIC acid: respiratory toxin produced in coconuts binds the inward facing (matrix)

48
Q

what are atractyloside and bongkrekic similar to?

A

oligomycin

49
Q

what couplers destroy the proton gradient?

A

asprin (ASA) , thermogenin(ucp1), ionophores

50
Q

what do uncoupler proteins do?

A

they create a “ proton leak” allowing protons to reenter the mitochondral matrix without capturing any ATP as energy

51
Q

why is theromgenin brown?

A

contains cytochrome containing mitochondria

52
Q

what is thermogenin?

A

a dissiptiation of the H+ gradient generated from ATP synthesis, to generate heat-also called uncoupling protein which results in loss of proton gradient
(leaky membrane)

53
Q

who has brown fat?

A

infants, neck and upper back as a biological heating pad

54
Q

what activates thermogenin?

A

hormone induced release of fatty acids form triglcerides

55
Q

what are ionophores?

A

uncouplers, which make the inner membrane permeable to compounds that cannot usually cross like ions

56
Q

what do ionophores and uncouplers have in common?

A

they allow for dissipitation of the proton gradient

57
Q

what types of ionophores are there?

A

channel formers (make a pore) and mobile carriers( transport back and forth)

58
Q

what is gramicidin?

A

channel forming ionophore

59
Q

what is valinomycin?

A

a mobile carrier( ionophor/ antibiotic of strep) and associated with carrying potassium across the bilayer

60
Q

since the inner membrane is impermeable to most proteins and enzyme, what is needed to help them pass the membrane?

A

shuttles to deliver electrons from NADH (from glycolysis in the cytosol) across the inner mitochondrial membrane

61
Q

what are the two shuttle mechanisms?

A

glycerol phosphate shuttle and malate-phospate shuttle

62
Q

do uncouplers affect the flow of electrons?

A

no, they enhance O2 and decrease ATP

63
Q

what is the equivalence of ATP to NADH

A

3 ATP

64
Q

what is the equivalence of ATP to FADH2?

A

2 ATP

65
Q

why does FADH2 result into less ATP?

A

because it bypasses complex 1

66
Q

what is the glycerol phosphate shuttle?

A

is a secondary mechanism from malate and it regenerates NAD+ from NADH to contribute to the oxidative phosphorylation pathway in the mitochondria to generate ATP

67
Q

what is the malate phosphate shuttle?

A

First, in the cytosol, malate dehydrogenase catalyses the reaction of oxaloacetate and NADH to produce malate and NAD+. In this process, two electrons generated from NADH, and an accompanying H+, are attached to oxaloacetate to form malate.

Once malate is formed, the first antiporter (malate-alpha-ketoglutarate) imports the malate from the cytosol into the mitochondrial matrix and also exports alpha-ketoglutarate from the matrix into the cytosol simultaneously. After malate reaches the mitochondrial matrix, it is converted by mitochondrial malate dehydrogenase into oxaloacetate, during which NAD+ is reduced with two electrons to form NADH and an H+ is released. Oxaloacetate is then transformed into aspartate (since oxaloacetate cannot be transported into the cytosol) by mitochondrial aspartate aminotransferase. Since aspartate is an amino acid, an amino radical needs to be added to the oxaloacetate. This is supplied by glutamate, which in the process is transformed into alpha-ketoglutarate by the same enzyme.

The second antiporter (the glutamate-aspartate antiporter) imports glutamate from the cytosol into the matrix and exports aspartate from the matrix to the cytosol. Once in the cytosol, aspartate is converted by cytosolic aspartate aminotransferase to oxaloacetate.

The net effect of the malate-aspartate shuttle is purely redox: NADH in the cytosol is oxidized to NAD+, and NAD+ in the matrix is reduced to NADH. The NAD+ in the cytosol can then be reduced again by another round of glycolysis, and the NADH in the matrix can be used to pass electrons to the electron transport chain so ATP can be synthesized.

68
Q

what will happen to the ETC cycle when hypoxia is present?

A

the rate of ETC WILL DECREASE AND ATP PRODUCTION WILL DECREASE

69
Q

When cellular ATP decrease what will happen?

A

anaerobic glycolysis, and lactic acid production, and MI- leading to tissue damage and leakage of CKMB, Troponin I and T

70
Q

does asprin uncouple or inhibit the ETC for oxidative phosphorylation?

A

it uncouples

biochemistry (28 decks)

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