Test Iii: Ch. 18 Electron Transport And Oxidative Phosphorylation

Front 1

What is the complete aerobic respiration of glucose reaction?

Back 1

C16H12O2 + 6 O2 --> 6 CO2 + 6 H2O + energy

Front 2

How do the products of the citric acid cycle contribute to the proton gradient?

Back 2

NADH and FADH2 generated from the TCA cycle are used by Complex 1 and 2 to pump protons

Front 3

How is a voltaic cell set us to find reduction potential?

Back 3

Solution 1 = 1 M X + 1 M X-

Solution 2 = 1 M H+ in equilibrium with 1atm H2 gas

Connect with salt bridge and voltmeter

Front 4

In a voltaic cell, if test solution takes electrons from the standard solution, the reduction potential is (positive/negative)?

Back 4

Positive

Front 5

How do we mathematically calculate free energy of redox reaction?

Back 5

Standard free energy change = -nF(reduction potential)

n = number of ions passing

F = faraday constant in mol*V

Front 6

Explain the flow of electrons through the ETC from NADH

Back 6

NADH --> NADH-Q reductase --> Ub --> Cytochrome c reductase complex --> cytochrome c --> cytochrome c oxidase complex --> O2

Front 7

Define cytochrome

Back 7

Protein with a heme cofactor

Front 8

What is the full name of complex I? What is its net reaction?

Back 8

NADH-Q Oxidoreductase aka NADH dehydrogenase

NADH + Q + 5 H+ matrix --> NAD+ + QH2 + 4 H+ cytoplasm

Net pumping of 1 proton into matrix

Front 9

How do electrons flow from NADH to Ubiquinone?

Back 9

Via complex I

1) NADH + FMN --> NAD+ + FMNH2

2) Through 2Fe-2S and 4Fe-4S clusters and to the Q pool

Front 10

Explain the proton pumping in NADH-Q oxidoreductase

Back 10

As e- flow through clusters, 4 H+ are pumped into the intermembrane space from matrix and 2 H+ get taken up from matrix to reduce Q

Front 11

What is the full name of complex II? What does it do? Does it pump protons?

Back 11

Succinate dehydrogenase

Takes FADH2's electrons, shuttles them through iron-sulfur complexes, and reduce Q to QH2

Does not pump protons

Front 12

What is the full name of Complex III? What does it do? How many protons does it pump?

Back 12

Transfers e- from ubiquinol (QH2) to cyt c through a His-coordinated Fe-S cluster and heme. Pumps 2 protons into the intermembrane space

Front 13

Describe the Q cycle that takes place in complex III

Back 13

1) QH2's electrons are transferred to Cyt C and Oxidized Q one at a time forming Cyt C1 and quinone radical with pumping of 2 protons

2) Step 1 repeats with generation of QH2 from quinone radical and Cyt C from cyt c1 with pumping of 2 more protons

Front 14

What is the full name of complex IV? What does it do?

Back 14

Cytochrome C oxidase transfers electrons from cytochrome c to O2 to make water

Front 15

Describe the flow of electrons through complex IV from cytochrome C to water

Back 15

2 Cytochrome c (4 e-) --> Cu A motif --> heme a --> heme a3 (one e- pair stops here) --> Cu 8 (another e- pair stops here) --> H2O

Front 16

Why are there two heme a's?

Back 16

They have the same heme group but distinct redox potentials due to their different protein environments

Front 17

Cytochrome C oxidase contains __ copper atoms coordinated to _____ side chains

Back 17

3 copper atoms coordinated to histidine sidechains

Front 18

How do we make water from reducing heme a3 and Cu 8?

Back 18

Once reduced, O2 acts as a bridge forming a heme (a3)-O-O-(Cu 8) peroxide bridge. The RO-OR' bond gets reduced initially to OH by 2 protons, then to two H2O by 2 more protons from the matrix

Front 19

What complex is most likely to produce ROS? What enzymes protect from ROS damage?

Back 19

Complex I

Superoxide dismutase and catalase

Front 20

How does superoxide dismutase do?

Back 20

E reduced + Radical O2 + 2 H+ --> H2O2 + E oxidized

Front 21

How does Catalase do?

Back 21

Catalse finishes the half assed job superoxide dismutase did.

2 H2O2 --> O2 + 2 H2O

Front 22

How does cyanide work and where in the ETC does it work?

Back 22

Cyanide binds ferric heme which is found in complex III and IV

Front 23

What does F0 F1 mean?

Back 23

F0 is the membrane bound proton conducting stick subunit

F1 is the matrix side ball subunit with ATPase activity

Front 24

What is the role of the proton gradient in ATPase?

Back 24

To release ATP from the synthase since ATP cannot leave the active site unless protons flow through the enzyme. Movement through the half-channels from a proton rich to a proton poor environment powers rotation of the c-ring

Front 25

Describve the structure of the c-ring

Back 25

3 alpha and 3 beta subunits arranged alternatively in a hexameric ring

P-loop NTPase members

gamma subunit in middle

Each member of the ring interacts with a different face of the gamma subunit

Front 26

Describe the O, T, and L sites of the c-ring

Back 26

O = Open: Product release and substrate binding ADP + Pi

L = Loose: ADP + Pi trapping

T = Catalysis ATP <-> ADP + Pi

Front 27

The gamma subunit rotates (degrees?) (clockwise/counterclock wise?) during ATP synthesis when viewed down the gamma subunit

Back 27

120 degrees counterclockwise

Front 28

Describe proton flow through ATPase

Back 28

1) Cytoplasmic protons enter half-channels (a subunit) where they interact with an Asp on the c subunit

2) Protonation of the Asp allows it to move through the hydrophobic environment of the membrane until it reaches a proton poor envrionment where the Asp is deprotonated

Front 29

How many proton drive 1 revolution of the ATPase? How many ATP do we generate per revolution? How many protons per ATP does that make it/

Back 29

10 protons per revolution

3 ATP/revolution

3.33 protons flow into the matrix/ATP

Front 30

What 2 pathways allow us to regenerate NAD+ in the cytoplasm?

Back 30

1) Glycerol-3-phosphate shuttle

2) Malate-Aspartate shuttle

Front 31

Describe the glycerol 3-phosphate shuttle mechanism. Where would we expect to see this mechanism occur?

Back 31

1) NADH reduces DHAP to form Glycerol 3-phosphate

2) Glycerol 3-phosphate is oxidized by FAD to FADH2

3) FADH2 reduces Q to QH2 which go to the Quinone pool

Found in muscle due to ability to sustain high levels of oxidative phosphorylation

Front 32

What enzymes catalyzes the entrance of cytoplasmic high-energy electrons into the ETC via the glycerol 3-phosphate shuttle?

Back 32

Glycerol 3-phosphate dehydrogenase catalyzes 2 reactions

1) NADH + DHAP <-> NAD+ + Glycerol 3-phosphate

2) FAD + Glycerol 3-phosphate <-> FADH2 + DHAP

Front 33

Describe electron flow in the malate-aspartate shuttle

Back 33

1) NADH + Oxaloacetate <-> NAD+ + Malate in the cytoplasm

2) Malate is antiported with alpha-ketoglutarate and then oxidized by NAD+ in the matrix to form NADH + Oxaloacetate

Front 34

How does the energy yield of NADH entering via the glycerol 3-phosphate shuttle differ from the energy yield of NADH entering via complex I? Why? Also what is complex I called?

Back 34

NADH entering via Glycerol 3-phosphate shuttle yields 1.5 ATP instead of 2.5 because FAD is the e- acceptor in complex I (NADH-Q oxidoreductase) enabling e- to flow against the NADH gradient

Front 35

What is the purpose of transaminating oxaloacetete to alpha-ketoglutarate once it has been formed by the oxidation of malate by NAD+ in the malate-shuttle?

Back 35

Alpha-ketoglutarate is then used to fuel the antiport of malate into the matrix by coupling the favorable alpha-ketoglutarate gradient to the unfavorable malate gradient

Front 36

What is the role of glutamate and aspartate in the malate shuttle?

Back 36

Glutamate donates an amino to oxaloacetate. Glutamate's deamination yields aspartate, and oxaloacetate's amination yields alpha-ketoglutarate.

The favorable aspartate gradient is then used to antiport against the unfavorable glutamate gradient.

Front 37

How does the role of glutamate and aspartate in the malate shuttle differ in the cytoplasm and matrix?

Back 37

In the cytoplasm, Asparate deaminates alpha-ketoglutarate to regenerate glutamate

The the matrix, Aspartate is used to couple antiport of glutamate into the matrix

Cytoplasmic glutamate is amino acceptor (cytoplasm) and donor (matrix)

Front 38

The glycerol 3-phosphate shuttle can take the place of ____ _____ to provide NAD+ in muscle

Back 38

Take place of lactate dehydrogenase

Front 39

What are the component of the ATP Synthasome?

Back 39

1) ATP-ADP translocase

2) F0F1 ATP synthase

3) Protons

4) Phosphate Carrier

Front 40

How many ATP are net yielded from the complete oxidation of glucose? How many does glycolysis, citric acid cycle, and oxidative phosphorylation yield respectively?

Back 40

30 Glucose/ complete oxidation

2 from Glycolysis

2 from Citric Acid cycle

26 from Oxidative phosphorylation

Front 41

How many high energy electrons are yielded from the complete oxidation of glucose? How many does glycolysis, citric acid cycle, and oxidative phosphorylation yield respectively? e

Back 41

2 NADH in glycolysis

2 NADH in the conversion of Pyruvate to Acetyl CoA

6 NADH + 2 FADH2 in the Citric Acid Cycle

2 NADH Oxidative phosphorylation

12 NADH + 2 FADH2 in complete oxdiation of glucose