Biochemistry: Oxidative Phosphorylation

Front 1

Electron carries of the respiratory chain are located where?

Back 1

Mitochondrial inner membrane

Front 2

Electron flow through the respiratory chain drives what?

Back 2

H+ transport out of the matrix

Front 3

ATP synthase is activated by what?

Back 3

H+ concentration gradient across the mitochondrial inner membrane

Front 4

Where does the respiratory chain and ATP synthase occur?

Back 4

In the inner membrane of the mitochondria

Front 5

In oxidative phosphorylation, electrons from NADH and FADH2 are used to do what?

Back 5

To reduce molecular oxygen to water

Front 6

The electron-transfer potential of NADH or FADH2 is converted into what?

Back 6

The phosphoryl-transfer potential of ATP

Front 7

Is NADH a strong or weak reducing agent? Does it have a positive or negative reduction potential?

Back 7

NADH is a STRONG reducing agent (wants to DONATE electrons) and it has a NEGATIVE reduction potential

Front 8

Is O2 a strong or weak oxidizing agent? Does it have positive or negative reduction potential?

Back 8

O2 is a STRONG oxidizing agent (wants to ACCEPT electrons) and it has a POSITIVE reduction potential.

Front 9

What is an oxidant (oxidizing agent)?

Back 9

An acceptor of electrons in a redox reaction

Front 10

What is a reductant (reducing agent)?

Back 10

A donator of electrons in an redox reaction

Front 11

What is DeltaE'o?

Back 11

Change in reduction potential (reduction minus oxidation)

Front 12

What is Coenzyme Q?

Back 12

CoQ is a hydrophobic molecule that shuttles protons and electrons about the inner mitochondrial membrane.

Front 13

Back 13

Reduced form of CoQ (QH2)

Front 14

ATP synthesis requires what uptake?

Back 14

H+ uptake

Front 15

Electrons are transferred from NADH to O2 through a chain of what 3 protein complexes?

Back 15

1. NADH-Q oxidoreductase

2. Q-cytochrome c oxidoreductase

3. Cytochrome c oxidase

Front 16

Electron flow within NADH-Q oxidoreductase, Q-cytochrome c oxidoreductase, and Cytochrome c oxidase leads to what?

Back 16

To the transport of protons across the inner mitochondrial membrane

Front 17

Electrons from FADH2 enter the electron-transport chain where?

Back 17

At the Q-cytochrome c oxidoreductase

Front 18

What is the purpose of Succinate-Q Reductase?

Back 18

Protein complex that contains succinate dehydrogenase that generates FADH2 in the citric acid cycle.

Front 19

Of the four protein complexes in the electron-transport chain, which do not transport protons?

Back 19

Succinate-Q Reductase

Front 20

Of the four protein complexes in the electron transport chain, which are proton pumps?

Back 20

1. NADH-Q oxidoreductase

2. Q-cytochrome c oxidoreductase

3. Cytochrome c oxidase

Front 21

The high-potential electrons of NADH enter the respiratory chain where?

Back 21

At the NADH-Q oxidoreductase (complex I)

Front 22

What are the 7 basic components of the electron transport chain?

Back 22

1. NADH

2.NADH-Q Oxidoreductase

3. Q (Coenzyme Q)

4. Q-Cytochrome c oxidoreductase

5. Cyt c

6. Cytochrome c oxidase

7. O2

Front 23

In the electron-transport chain, the electron transfer steps are in order of what?

Back 23

Reduction potential, i.e., electron affinity of the components INCREASES as electrons move down the chain.

Front 24

The flow of 2 electrons from NADH to CoQ through NADH-Q oxidoreductase leads to what?

Back 24

To the pumping of FOUR hydrogen ions out of the matrix of mitochondrion.

Front 25

What is the function of Q-cytochrome c oxidoreductase?

Back 25

Catalyze the transfer of electrons from QH2 produced by NADH-Q oxidoreductase and the succinate-Q reductase complex to oxidized cytochrome c

Front 26

How many protons are pumped out of the matrix per NADH?

Back 26

10

Front 27

NADH-Q Oxidoreductase pumps out of the matrix how many protons?

Back 27

4

Front 28

Q-Cytochrome c oxidoreductase pumps out of the matrix how many protons?

Back 28

4

Front 29

Cytochrome c oxidase pumps out of the matrix how many protons?

Back 29

2

Front 30

How does Q-cytochrome c oxidoreductase pump out 4 H+ but only take in 2+?

Back 30

The 2 extra H+ that are being released are from QH2 in the membrane

Front 31

How does cytochrome c oxidase pump out 2 H+ even though it takes in 4 H+?

Back 31

Because 2 H+ go to 1/2O2 to form water in the membrane

Front 32

How many protons are pumped out of the matrix per FADH2?

Back 32

6

Front 33

The inner mitochondrial membrane has low permeability for H+ except for what?

Back 33

ATP synthase

Front 34

What is the Proton-Motive Force?

Back 34

The energy-rich, unequal distribution of protons between the matrix and cytoplasm of a mitochondrion.

Front 35

The electron transport chain and ATP synthase are biochemically separate systems linked by what?

Back 35

Proton-motive force

Front 36

Label each part

Back 36

a = proton channel

b2 = stator

c ring = proton rotor

gamma = cam shaft

Beta = ATP synthesis site

Front 37

The F1 subunit of ATP sythase is composed of how many alpha and beta subunits?

Back 37

3 alpha

3 beta (active sites)

Front 38

What drives the ATP synthase motor?

Back 38

H+

Front 39

ATP synthase catalyzes what?

Back 39

The formation of ATP from ADP and orthophosphate (HPO4-2)

Front 40

The moving unit, or rotor, of ATP synthase consists of what?

Back 40

C ring, and the gamma-epsilon stalk

Front 41

The stationary unit, or stator, of ATP synthase consists of what?

Back 41

Everything EXCEPT the c ring and the gamma-epsilon stalk

Front 42

What are the 3 steps of the beta subunit in the process of ATP synthesis?

Back 42

1. Trapping of ADP and Pi

2. ATP synthesis

3. ATP release and ADP and Pi building

Front 43

At any given moment, one of the three beta subunits will be in what 3 conformations?

Back 43

1. L - loose (ADP and Pi binding)

2. T - tight (ATP synthesis)

3. O - open (ATP release)

Front 44

What drives ATP synthesis in ATP synthase?

Back 44

The rotation of the gamma cam shaft

Front 45

The gamma cam shaft rotates how many degrees and in what direction?

Back 45

120 degrees counter clock wise

Front 46

Transport of ATP from mitochrondria to cytosol in exchange for ADP and pi costs what?

Back 46

1 H+

Front 47

Cytosolic NADH from glycolsis can do what?

Back 47

Can enter the mitochondrial electron-transport chain by reducing dihydroxyacetone phosphate to glycerol 3-phosphate via glycerol 3-phosphate dehydrogenase

Front 48

Glycerol 3-phosphate goes on to do what in the glycerol 3-phosphate shuttle?

Back 48

It is reoxidized to dihydroxyacetone phosphate on the inner mitochondrial membrane and its electrons go to FAD to form FADH2 which enters the respiratory chain as QH2.

Front 49

When cytoplasmic NADH transported by the glycerol 3-phosphate shuttle is oxidized by the respiratory chain, how many ATP are formed? Why?

Back 49

1.5 instead of 2.5 because the electrons from NADH are carried to the respiratory chain via FAD against its concentration gradient hence uses 1 ATP

Front 50

How many H+ are needed to make 1 ATP?

Back 50

3 H+ are needed to turn gamma 1/3 to make 1 ATP

Front 51

What is the yield of ATP from NADH?

Back 51

10 H+ pumped out/4 return per ATP made = 2.5 ATP made per NADH

Front 52

What is the yield of ATP from FADH2?

Back 52

6 H+ pumped out/4 return per ATP made = 1.5 ATP made per FADH2

Front 53

The complete oxidation of glucose yields how many molecules of ATP?

Back 53

30!

Front 54

What is the net yield of ATP from glycolysis?

Back 54

2 ATP

Front 55

What is the net yield of ATP from the citric acid cycle?

Back 55

2 ATP

Front 56

What is the net yield of ATP from oxidative phosphorylation?

Back 56

26 ATP

Front 57

2 NADH are formed in glycolysis. Assuming what, how many ATPs are formed?

Back 57

Assuming transport of NADH by the glycerol 3-phosphate shuttle, 1.5 ATP are formed per NADH

Front 58

2 NADH are formed in the oxidative decarboxylation of pyruvate. How many ATP molecules are formed?

Back 58

2 NADH forms 5 ATP

Front 59

2 FADH2 formed in the citric acid cycle yields how much ATP?

Back 59

3 ATP

Front 60

6 NADH formed in the citric acid cycle yield how much ATP?

Back 60

15 ATP

Front 61

Electrons do not usually flow through the electron-transport chain to O2 unless what is true?

Back 61

Unless ADP is simultaneously phosphorylated to ATP

Front 62

The level of ADP determines what?

Back 62

The rate of oxidative phosphorylation

Front 63

If [ADP] is high, what happens to oxidative phosphorylation?

Back 63

Oxidative phosphorylation increases

Front 64

At rest, low concentrations of ADP, means what for NADH and FADH2 produced by the citric acid cycle?

Back 64

They are not oxidized back into NAD+ and FAD by the electron-transport chain and thus the citric acid cycle SLOWS.

Front 65

Some organisms possess the ability to do what?

Back 65

Uncouple oxidative phosphorylation from ATP synthesis to generate heat!

Front 66

What does it do?

Back 66

2,4-Dinitrophenol (DNP) is an uncoupler that is TOXIC to eat and inhibits ATP sythesis.

Front 67

What is uncoupling protein 1?

Back 67

Uncoupling protein that generates heat by permitting the influx of protons into the mitochondria without the ATP synthesis.