01c: Oxidative Phosphorylation

Question 1

Ox Phos: respiration depends on and is coupled to (X).

Answer 1

X = ATP phosphorylation

Question 2

Experimentally adding mitochondria with succinate and P. What should be added to initiate oxygen consumption?

Answer 2

ADP

Question 3

List the P/O ratios for NADH and FADH2.

Answer 3

NADH: 3 (new is 2.5)
FADH2: 2 (new is 1.5)

Question 4

Experimentally adding mitochondria with succinate and P. Adding DNP will cause (stimulation/inhibition) of oxygen consumption.

Answer 4

Stimulation (without ADP) and rapid oxygen consumption;

DNP is an “uncoupler”

Question 5

Experimentally adding mitochondria with succinate and P. After adding an inhibitor of ETC, what do you have to add to initiate oxygen consumption?

Answer 5

You can’t.. if the entire ETC is inhibited, oxygen consumption won’t occur

Question 6

Experimentally adding mitochondria with succinate and P. After adding an inhibitor of phosphorylation, what do you have to add to initiate oxygen consumption?

Answer 6

DNP (uncoupler); even if phosphorylation inhibited, respiration can then proceed on its own

Question 7

List the flavin carriers in ETC. How many hydrogens/electrons does each transport?

Answer 7

FAD and FMN;

2 hydrogens and electrons (FADH2, FMNH2)

Question 8

The non-heme iron, aka (X), proteins are ETC carriers that transport (Y) number of hydrogens/electrons.

Answer 8

X = FeS;
Y = 1 electron

Question 9

The heme iron, aka (X), proteins are ETC carriers that transport (Y) number of hydrogens/electrons.

Answer 9

X = cytochromes;
Y = 1 electron

Question 10

CoQ, aka (X), is an ETC carrier that transport (Y) number of hydrogens/electrons.

Answer 10

X = Ubiquinone
Y = 2 hydrogens and electrons (QH2)

Question 11

NADH gets oxidized by ETC complex (1/2/3/4), formally called (X), which passes the electrons to (Y).

Answer 11

Complex I
X = NADH-Q Reductase
Y = CoQ

Question 12

CoQ receives electrons from which complex(es)?

Answer 12

1. Complex I (NADH-Q reductase)
2. Complex II (succinate dehydrogenase)
3. ACD (acyl-CoA dehydrogenase)
4. GPDHm (mito G3P dehydrogenase)

Question 13

CoQ in ETC passes its electrons to (X).

Answer 13

X = Complex III (QH2-cytochrome c reductase)

Question 14

Complex III passes electrons to (X) and then they’re passed to (Y).

Answer 14

X = cytochrome c
Y = Complex IV (cytochrome oxidase)

Question 15

(X), the final electron acceptor in ETC, takes the electrons from (Y) carrier.

Answer 15

X = O2
Y = Complex IV (cytochrome oxidase)

Question 16

T/F: All ETC complex pump H out of mitochondria matrix.

Answer 16

False - only complex I, III, IV

Question 17

Which complex is the ATP synthase?

Answer 17

Complex V

Question 18

Rotenone amytal inhibits (X) complex of ETC. Can electrons still get to CoQ?

Answer 18

X = Complex I (NADH-Q reductase)

Yes, via FAD dehydrogenases

Question 19

Antimycin A inhibits (X) complex of ETC. Can electrons still get to CoQ?

Answer 19

X = Complex III (QH2-cytochrome c reductase)

Yes, but ETC won’t work since can’t get past complex III

Question 20

CO is dangerous partly due to its inhibition of (X) ETC carrier.

Answer 20

X = Complex IV (cytochrome oxidase)

Question 21

Oligomycin is dangerous due to its inhibition of (X) ETC carrier.

Answer 21

X = Complex V (ATPase)

Question 22

ETC: The function of the (X) and (Y) shuttles is to shuttle what to where?

Answer 22

X = glycerol-P
Y = malate-asp 

Reducing equivalents from cytosol into mitochondria (to ETC)

Question 23

Which enzyme is key for the glycerol-P shuttle? Its product, (X), is capable of passing (Y).

Answer 23

G3P dehydrogenase
X = G3P or Dihydroacyteone-P (depending on direction of reaction)
Y = mito membranes

Question 24

In glycerol-P shuttle, the electrons are taken from (X) and given eventually to (Y).

Answer 24

X = NADH
Y = FAD (to become FADH2)

Question 25

In malate-asp shuttle, (X) takes electrons from (NADH/FADH2) and becomes (Y). Which enzyme catalyzes this?

Answer 25

X = oxaloacetate;
NADH;
Y = malate
Malate dehydrogenase

Question 26

T/F: Malate can cross mito membranes.

Answer 26

True

Question 27

In malate-asp shuttle, the electrons are taken from (X) and given eventually to (Y).

Answer 27

X = Y = NADH

Question 28

Aspartate aminotransferase (AST) is important enzyme in (X) because it converts (Y) to (Z).

Answer 28

X = Malate-asp shuttle
Y = oxaloacetate and Glu
Z = aspartate and alpha-ketoglutarate

(which can cross mito membrane)

Question 29

One of the first tests for liver damage is measuring (X) enzyme levels in blood, which would be (increased/decreased).

Answer 29

X = AST (Aspartate aminotransferase);

Increased (leak out of cells)

Question 30

All else equal, there is a difference of (X) ATP yield per glucose depending on if glycerol-P or Malays-asp shuttle used.

Answer 30

X = 2

Theoretically, GP shuttle gives 36 and M-A shuttle 38

Question 31

ETC: Membrane potential exists due to (X) process, which drives ATP (into/out of) mito.

Answer 31

X = H pumping (membrane more positive on outside);

Out via ANT (Adenosine NT Translocase) since ATP more negative than ADP

Question 32

What’s the mechanism of ETC uncoupling by poisons?

Answer 32

Carry protons across membrane to collapse H gradient

Question 33

T/F: In cases of ETC uncoupling, the ETC keeps pumping, despite lack of ATP synthesis.

Answer 33

True

Question 34

Actual ATP yield is (more/less) than the theoretical yield per glucose. Why?

Answer 34

Less (30 ATP);

Some E from proton needed to maintain membrane potential and drive ANT (Adenine NT translocase)

Question 35

ANT (Adenosine NT translocase) is important because it provides (X) with (Y). Explain.

Answer 35

X = ATP synthase
Y = ADP

Exchanges ATP (out) for ADP (into mito)

Question 36

Oligomycin inhibits (electron transport/mito phosphorylation).

Answer 36

Mito phosphorylation