cell integrity

Question 1

what is substrate level phosphorylation?

Answer 1

when ATP or its equivalents are produced directly by kinase

Question 2

where is the bulk of ATP produced?

Answer 2

oxidative phosphorylation in the inner mitochondrial membrane

Question 3

what are cristae (mitochondria)

Answer 3

folds of the inner membrane increasing surface area

Question 4

where does oxidative phosphorylation take place?

Answer 4

inner membrane of mitochondria

Question 5

outline the reaction of NADH re-oxidation

Answer 5

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

Question 6

outline the reaction of FADH2 re-oxidation

Answer 6

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

Question 7

what does the electron transport chain consist of?

Answer 7

4 membrane proteins : complex I-IV

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

Question 8

other names for complex I

Answer 8

NADH-Q oxidoreductase or NADH dehydrogenase

Question 9

other names for complex II

Answer 9

succinate-Q reductase or succinate dehydrogenase

Question 10

other names for complex III

Answer 10

Q-cytochrome C oxidoreductase

Question 11

other names for complex IV

Answer 11

cytochrome c oxidase

Question 12

other name for co-enzyme Q

Answer 12

ubiquinone

Question 13

which complexes do protons pass through?

Answer 13

I,III and IV

Question 14

where else is complex II used?

Answer 14

Krebs cycle (succinate dehydrogenase)

Question 15

where does FADH2 enter the electron transport chain?

Answer 15

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

Question 16

define redox reactions

Answer 16

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

Question 17

what is a redox couple?

Answer 17

a substrate that can exist in both oxidised and reduced forms

Question 18

what is a redox potential?

Answer 18

the ability of a redox couple to accept or donate electrons

Question 19

what reference do standard redox potentials use?

Answer 19

hydrogen electrode

Question 20

what does a negative E0 imply?

Answer 20

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

Question 21

what does a positive E0 imply?

Answer 21

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

Question 22

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

Answer 22

they lose energy

Question 23

what type of enzyme is ATP synthase?

Answer 23

multimeric

Question 24

what are the parts of ATP synthase?

Answer 24

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

Question 25

how does the enzyme alter affinities for ATP and ADP?

Answer 25

by rotating due to proton flow

Question 26

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

Answer 26

Pi + ADP ————> ATP

Question 27

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

Answer 27

ATP ———–> Pi + ADP

Question 28

what is the most common cause of oxidative phosphorylation failure?

Answer 28

lack of oxygen
hypoxia- diminished
anoxia- total

Question 29

what is oxygen uptake of mitochondria controlled by?

Answer 29

ADP and Pi

Question 30

what are metabolic poisons?

Answer 30

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

Question 31

how is cyanide and azide a metabolic poison?

Answer 31

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

Question 32

how is malonate a metabolic poison?

Answer 32

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

Question 33

how is rotenone a metabolic poison?

Answer 33

inhibits transfer of electrons from complex I to ubiquinone

Question 34

how is oligomycin a metabolic poison?

Answer 34

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

Question 35

how is dinitrophenol(DNP) a metabolic poison?

Answer 35

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