cell integrity Flashcards

1
Q

what is substrate level phosphorylation?

A

when ATP or its equivalents are produced directly by kinase

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2
Q

where is the bulk of ATP produced?

A

oxidative phosphorylation in the inner mitochondrial membrane

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3
Q

what are cristae (mitochondria)

A

folds of the inner membrane increasing surface area

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4
Q

where does oxidative phosphorylation take place?

A

inner membrane of mitochondria

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5
Q

outline the reaction of NADH re-oxidation

A

NADH + H+ + 1/2O2 ——> NAD+ + H2O ΔG -223Kj/mol

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6
Q

outline the reaction of FADH2 re-oxidation

A

FADH2 + H+ + 1/2O2 ——> FAD + H2O ΔG -170Kj/mol

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7
Q

what does the electron transport chain consist of?

A

4 membrane proteins : complex I-IV

2 mobile electron carriers: co-enzyme Q and cytochrome C

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8
Q

other names for complex I

A

NADH-Q oxidoreductase or NADH dehydrogenase

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9
Q

other names for complex II

A

succinate-Q reductase or succinate dehydrogenase

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10
Q

other names for complex III

A

Q-cytochrome C oxidoreductase

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11
Q

other names for complex IV

A

cytochrome c oxidase

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12
Q

other name for co-enzyme Q

A

ubiquinone

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13
Q

which complexes do protons pass through?

A

I,III and IV

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14
Q

where else is complex II used?

A

Krebs cycle (succinate dehydrogenase)

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15
Q

where does FADH2 enter the electron transport chain?

A

complex II so skips a proton (one less proton and so less ATP produced than NADH)

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16
Q

define redox reactions

A

electron transfer reactions involving a reduced substrate(which donates electrons and becomes oxidised) and an oxidised substrate(which accepts electrons and becomes reduced)

17
Q

what is a redox couple?

A

a substrate that can exist in both oxidised and reduced forms

18
Q

what is a redox potential?

A

the ability of a redox couple to accept or donate electrons

19
Q

what reference do standard redox potentials use?

A

hydrogen electrode

20
Q

what does a negative E0 imply?

A

the redox couple has a tendency to donate electrons(more reducing power than hydrogen)

21
Q

what does a positive E0 imply?

A

the redox couple has a tendency to accept electrons(more oxidising power than hydrogen)

22
Q

what happens to the electrons as they are passed down the electron transport chain?

A

they lose energy

23
Q

what type of enzyme is ATP synthase?

A

multimeric

24
Q

what are the parts of ATP synthase?

A

membrane bound F0 and an F1 part which projects into the matrix space

25
Q

how does the enzyme alter affinities for ATP and ADP?

A

by rotating due to proton flow

26
Q

if protons flow into matrix space what is the reaction on ATP synthase?

A

Pi + ADP ————> ATP

27
Q

if protons flow out of matrix space what is the reaction on ATP synthase?

A

ATP ———–> Pi + ADP

28
Q

what is the most common cause of oxidative phosphorylation failure?

A

lack of oxygen
hypoxia- diminished
anoxia- total

29
Q

what is oxygen uptake of mitochondria controlled by?

A

ADP and Pi

30
Q

what are metabolic poisons?

A

molecules that interfere with electron flow in the ETC or with proton flow

31
Q

how is cyanide and azide a metabolic poison?

A

binds with high affinity to ferric(Fe3+) form of the haem group in cytochrome oxidase complex blocking the final step of the ETC

32
Q

how is malonate a metabolic poison?

A

closely resembles succinate (competitive inhibitor) so binds to succinate dehydrogenase slowing down electron flow from succinate to ubiquinone by inhibiting oxidation of succinate to fumarate

33
Q

how is rotenone a metabolic poison?

A

inhibits transfer of electrons from complex I to ubiquinone

34
Q

how is oligomycin a metabolic poison?

A

antibiotic which binds to the ‘stalk’ of ATP synthase and blocking flow of protons through the enzyme

35
Q

how is dinitrophenol(DNP) a metabolic poison?

A

is a proton ionophore which can shuttle protons across the inner mitochondrial membranes