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GI > Mitochondrial synthesis of ATP > Flashcards

Mitochondrial synthesis of ATP Flashcards

1
Q

what is the approximate concentration of ATP in cells

A

6mM

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2
Q

what is the turnover of ATP per day?

A

75kg/day

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3
Q

how much of the energy from food produces ATP?

A

around 1/2

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4
Q

what is the permeability of the outer membrane of mitochondria to substances?

A

freely permeable if

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5
Q

what is characteristic of the inner mitochondrial membrane?

A

cristae!

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6
Q

what does the inner membrane of mitochondria control?

A

entry/ exit of molecules

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7
Q

what sort of insulator is the inner membrane of mitochondria?

A

electrical insulator

by controlling movement of ions

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8
Q

what types of transporters are within the inner membrane of mitchondria?

A

more protein than lipid transporters

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9
Q

what is the concentration of metabolites and ions like in the intermembrane space of mitochondria?

A

similar to cytosol

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10
Q

what substances are found within the matrix of mitochondria?

A

lots of enzymes
high concentration of substrates, cofactors, ions
mitochondrial DNA, RNA, ribosomes (most proteins encoded on nuclear DNA)

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11
Q

where does the link reaction occur?

A

matrix of mitchondria

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12
Q

what happens to pyruvate in the link reaction?

A

becomes acetyl coA

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13
Q

what is the key decision point of the link reaction and why?

A

pyruvate dehydrogenase

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14
Q

what inhibits the link reaction?

A

high energy levels so high ratio of NADH: NAD and high ratio of ATP: ADP and high levels of acCOa

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15
Q

what happens to NAD in the link reaction?

A

reduced to NADH

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16
Q

which cofactor is required for pyruvate dehydrogenase?

A

B1/ thiamin

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17
Q

what does B1/thiamin deficiency result in?

A

neurological problems/ cardiovascular symptoms

in alcohol addicts –> Wernicke Korsakoff syndrome

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18
Q

where does the krebs/ citric acid cycle take place?

A

mitochondria matrix

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19
Q

what activates pyruvate dehydrogenase enzyme?

A

high levels of Ca signalling sudden demand for energy

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20
Q

which 3 enzymes are key to the krebs cycle?

A

citrate synthese, isocitrate dehydrogenase, a-ketoglutarate dehydrogenase

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21
Q

what happens during stage 1 of the krebs cycle?

A

acetyl coA –> 6C citrate –> 4C succinyl coA + 2CO2

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22
Q

how many CO2 molecules are released in the 1st stage of the krebs cycle?

A

2 CO2

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23
Q

what happens during the 2nd stage of the krebs cycle?

A

oxidation of 4C compound –> oxaloacetate

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24
Q

what are the products of the krebs cycle?

A

3NADH, FADH2, 2CO2, GTP,

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25
Q

what percentage of cellular ATP is produced in mitochondria under aerobic conditions?

A

95%

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26
Q

what does the concentration of intermediates in the krebs cycle depend on?

A

other reactions in the cell

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27
Q

what are intermediates in the krebs cycle exchanged for?

A

other metabolic pathways

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28
Q

which pathways may use krebs cycle intermediates as building blocks?

A

anabolic/ synthetic pathways

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29
Q

why does ketone synthesis occur in DMT1?

A

glycolysis inhibited, low pyruvate
oxaloacetate and malate removed from the krebs cycle to be used in gluconeogenesis
fatty acids oxidised for energy –> XS acteyl CoA because of lack of oxaloacetate therefore broken down into ketones –> ketoacidosis

30
Q

which 2 processes are tightly coupled in oxidative phosphorylation?

A

electron transport and ATP synthesis

31
Q

what happens during electron transport?

A

oxidation

32
Q

what happens during ATP synthesis?

A

phosphorylation

33
Q

what does the electron transport create?

A

proton gradient

34
Q

what does ATP synthesis require?

A

proton gradient

35
Q

which 2 cofactors are involved in electron transport?

A

NADH and FADH2

36
Q

what supplies energy to electron transport?

A

electrons

37
Q

what supplies energy to ATP synthesis (in oxidative phosphorylation?

A

proton gradient

38
Q

how many complexes are involved in electron transport?

A

4 (I, II, III, IV)

39
Q

which complexes are transmembrane?

A

I, III, IV

40
Q

what are the 2 other electron carriers in the membrane needed for electron transport?

A

ubiquinone, cytochrome C

41
Q

which complex does NADH give an H to?

A

complex I

42
Q

which complex does FADH2 give H to?

A

complex II

43
Q

what is the final electron acceptor of the electron transport chain?

A

oxygen

44
Q

what happens to oxygen in the electron transport chain?

A

combines with electrons and 2 protons –> water

45
Q

where does cyanide inhibit electron transport?

A

blocks the reduction of oxygen to water

46
Q

where does oxidative phosphorylation occur in the mitochondria?

A

across the inner mitochondrial membrane (well insulated membrane)

47
Q

where is the concentration of H lower in mitochondria?

A

in the matrix

48
Q

which complexes translocate H across the membrane?

A

I, III, IV

49
Q

which direction are H ions translocated?

A

from matrix into intermembrane space

50
Q

how many H are translocated per NADH?

A

4

51
Q

why does FADH2 cause fewer H to be translocated?

A

it releases electrons into the electron transport chain later than NADH

52
Q

What does the F0F1 ATPase do?

A

synthesises ATP

53
Q

What is the name of the antiporter that transports ADP and ATP?

A

adenine nucleotide transporter

54
Q

Which other transporters exists in addition to F0F1ATPase and adenine nucleotide transporter?

A

Pi and H

55
Q

how many H move through ATPase?

A

3

56
Q

why does the movement of H down the conc gradient cause ATP to be produced?

A

it causes physical movement pushing the proteins around like a motor

57
Q

which direction does ATP move through the antiporter and why?

A

matrix into intermembrane space so ATP can be released and used!

58
Q

Why does one H move through the transporter as one Pi moves into the matrix?

A

to maintain electroneutrality as Pi is negatively charged

59
Q

why can ATP synthesis not occur without electron transport?

A

electron transport required to set up the proton gradient

60
Q

why might there be a problem with ATPase?

A

lack of ADP

61
Q

why might electron transport be inhibited?

A

lack of oxygen or reduced cofactor substrates

62
Q

why does a problem with ATPase stop electron transport?

A

H concentration builds up in intermembrane space so H can move down concentration gradient through complexes

63
Q

how many H move across the inner mitochondrial membrane to the matrix per 1 ATP synthesised?

A

4 (3 through synthase 1 through H transporter)

64
Q

what are uncouplers?

A

weak acids

65
Q

what happens in uncoupling?

A

uncouple oxidation from phosphorylation

66
Q

what effect do uncouplers have on the H gradient?

A

dissipates

67
Q

what happens to electron transport and ATP synthesis?

A

electron transport can continue but ATP synthesis inhibited

68
Q

which natural uncoupler protein exists in mitochondria in brown adipose tissue?

A

thermogenin

69
Q

what is energy released as in brown adipose tissue?

A

heat

70
Q

what activates thermogenin in brown adipose tissue?

A

decrease in core body temp, increase in NA released, increase in fatty acids in cytosol, activates thermogenin

GI (10 decks)

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