L2_ ETC and OP

Question 1

oxidation of food molecules to produce energy (in the form of ATP) through a series of cytoplasmic and mitochondrial-linked enzymatic pathways

Answer 1

Cellular respiration

Question 2

Between O2 and CO2, which among these two molecules are being consumed and which is being produced during cellular respiration?

Answer 2

consumed - O2

Produced - CO2

Question 3

Stages of Cellular respiration

Answer 3

Digestion of food polymers

production of acetyl CoA (glycolysis and/or fatty acid oxidation)

Oxidation of acetyl CoA to Co2 and H2O (Krebs Cycle and electron transport chain)

Question 4

4 pathways of respiration

Answer 4

Glycolysis

Krebs Cycle

Electron Transport Chain (ATP)

ATP synthesis

Question 5

Respiration pathway involving the conversion of glucose to pyruvate, NADH, and ATP

Answer 5

Glycolysis

Question 6

Respiration pathway involving the conversion of Acetyl CoA to Co2, FADH2, GTP, and NADH

Answer 6

Krebs Cycle

Question 7

Respiration pathway involving the passage of electrons from NADH and FADH2 to O2

Answer 7

Electron Transport Chain (ETC)

Question 8

Pathway of respiration which involves the enzyme ATP synthase that synthesizes the ATP

Answer 8

ATP synthesis

Question 9

A series of reaction wherein electrons and H+ from NADH and FADH2 are passed to intermediate carriers before being accepted ultimately by O2 to produce H2O

Answer 9

Electron Transport Chain

Question 10

What two half reactions are involved at the start of ETC?

Question 11

What reduction half reaction is involved at the end of ETC?

Question 12

Why ETC is important?

Answer 12

to control the release of energy for the synthesis of ATP and avoid the explosive release of energy as heat and light energy

Question 13

Why is ETC considered as a “downhill” flow of electron?

Answer 13

because it starts with high-energy molecules to low energy molecules (H2O)

Question 14

In the ETC series of reaction, where can you find the lowest standard reduction potential and the highest standard reductions potential?

Answer 14

lowest E° - at the start (reactants) of ETC (NADH and FADH2)

Highest E° - at the end (products) of ETC (NAD+ and FAD)

Question 15

Where does the ETC occur in eukaryotes?

Answer 15

In the inner membrane of mitochondria

Question 16

What are the protein complexes in ETC?

Answer 16

Complex I (NADH dehydrogenase)

Complex II (Succinate CoQ oxidoreductase)

Complex III (Cytochrome bc1 complex)

Complex IV (Cytochrome c oxidase)

Question 17

These are the intermediate electron carries embedded in the inner mitochondrial membrane

Answer 17

ETC protein complexes

Question 18

In the inner mitochondrial membrane, what is the charge present outside and inside?

Answer 18

Outside (+)

Inside (-)

Question 19

Describe the pH gradient inside and outside the inner mitochondrial membrane.

Answer 19

Alkaline inside (-)

Acidic outside (+)

Question 20

Describe the charge difference inside and outside the inner mitochondrial membrane.

Answer 20

+ outside

• inside

Question 21

What force is generated by proton pumping?

Answer 21

Proton-motive force

Question 22

How is proton-motive force generated?

Answer 22

By proton pumping which results in higher concentration of H+ (protons) in the intermembrane space causing electrochemical gradient (pH gradient + membrane potential)

Question 23

Subunits of ATP synthase

Answer 23

F1 and F

Question 24

What drives the electron movement from NADH and FADH2 in the ETC?

Answer 24

the overall ΔG°’ = -219.99kJ/mol (in NADH) & -200.69kJ/mol (in FADH2)

Question 25

What the net standard reduction potential (ΔE°') of the reaction involving the reaction of NADH to NAD+ in the ETC?

Answer 25

ΔE°' = +1.14V

Question 26

What the net standard reduction potential (ΔE°') of the reaction involving the reaction of FADH2 to FAD in the ETC?

Answer 26

ΔE°' = +1.04 V

Question 27

Given the net standard reduction potential (ΔE°') of the reaction involving the transport of 2 electrons from NADH to NAD+ in the ETC which is equal to +1.14V, what would be the overall free energy change (ΔG°') in kJ/mol to carryout a single ETC series of this reaction?

Answer 27

ΔG°' = -219.99kJ/mol

Question 28

If you are given a value of the net standard reduction potential of a cell and asked to compute for the overall free energy change, what formula are you going to use?

Answer 28

ΔG°' = -nFΔE°'

Question 29

Given the net standard reduction potential (ΔE°') of the reaction involving the redox reaction of FADH2 to FAD in the ETC which is equal to +1.04V with a 2 net electrons transferred, what would be the overall free energy change (ΔG°') kJ/mol to carryout a single ETC series of this reaction?

Answer 29

-200.69kJ/mo

Question 30

Given the net standard reduction potential (ΔE°') of the reaction involving the transport of 2 electrons from NADH to NAD+ in the ETC which is equal to +1.14V, what would be the overall free energy change (ΔG°') in kcal/mol to carryout a single ETC series of this reaction?

Answer 30

-52.58 kcal/mol

Question 31

Given the net standard reduction potential (ΔE°') of the reaction involving the redox reaction of FADH2 to FAD in the ETC which is equal to +1.04V with a 2 net electrons transferred, what would be the overall free energy change (ΔG°') kcal/mol to carryout a single ETC series of this reaction?

Answer 31

-47.96 kcal/mol

Question 32

What is the overall free energy change of the oxidation of NADH to NAD+ in the ETC kJ/mol?

Answer 32

-219.99kJ/mol

Question 33

What is the overall free energy change of the oxidation of FADH2 to FAD in the ETC in kJ/mol?

Answer 33

-200.69kJ/mol

Question 34

If you are told that the electron flow in the ETC results in the transfer of protons (H+) from the matrix to the intermembrane space, what do you think are protein complexes involved?

Answer 34

Complexes I, III, & IV

Question 35

If you are told that the transfer of electrons in the ETC did not results to proton transfer, what protein complex do you think is involved?

Answer 35

Complex II

Question 36

What is the ultimate electron acceptor in the ETC?

Answer 36

O2

Question 37

What product is formed in the final electron transfer of ETC?

Answer 37

H2O

Question 38

How many protons are pumped from each of the protein complexes in the ETC?

Answer 38

CI & CII - 4 CII - NONE CIV - 2

Question 39

What co-factor is involved in the transport of electron from complex I/II to complex III in the ETC?

Answer 39

Ubiquinone (CoQ)

Question 40

What co-factor is involved in the transfer of electrons from Complex II to Complex IV?

Answer 40

Cytochrome C

Question 41

What is the role of iron ions (Fe3+ and Fe2+) molecules in ETC?

Answer 41

Redox reactions in the protein complexes (Fe3+ can be oxidized & Fe2+ can be reduced)

Question 42

What molecules or cofactors are involved in the transport of electrons in complex I of ETC?

Answer 42

FMN FMNH2 2 Iron-sulfur protein -2Fe(III)SP

Question 43

What ions are primarily involved in the redox reactions in all 4 protein complexes in the ETC?

Answer 43

Iron (Fe3+ & Fe2+)

Question 44

Describe the difference in the flow of ETC betwen NADH & FADH2.

Answer 44

NADH-enters complex one electron is transferred to FMN resulting to FMH2 then transferred to 2Fe(III)SP pumping 4 protons to the intermembrane space of mitochondria; electron is then transport by CoQ forming CoQH2 to CIII with 2 redox reactions between Fe2+ and Fe3+ then to CIV via cytochrome c and to 1/2 O2 forming H2O FADH2 - does not enter CI, CII immediately via CoQ and similar reactions involved in NADH continue

Question 45

an enzyme complex containing the catalytic site for the synthesis of ATP

Answer 45

ATP synthase

Question 46

Proton-conducting unit of ATP synthase

Answer 46

F0 subunit

Question 47

ATP synthase subunit where the ATP synthesis occurs

Answer 47

F1

Question 48

Is the ATP production via ATP Synthase an endergonic or exergonic reaction?

Answer 48

Endergonic (ΔG°' = +30.5kJ/mol)

Question 49

Apart from ATP, what is the other product produced via the reduction of ADP+Pi+H+ in the synthesis of ATP?

Answer 49

H2O

Question 50

The reaction involved in the synthesis of ATP via ATP synthase in very endergonic, how is this reaction made to proceed?

Answer 50

via Chemiosmotic hypothesis

Question 51

Who proposed the Chemiosmotic Hypothesis?

Answer 51

Peter Mitchell

Question 52

How does chemiosmotic hypothesis works?

Answer 52

electron transport and ATP synthesis are coupled by a proton gradient (pH gradient and membrane potential) across the inner mitochondrial membrane; upon creation of a proton gradient, protons flow back to the matrix via the F0 subunit of ATP synthase to equalize charge distribution and by doing so, drives synthesis of ATP by ATP synthase

Question 53

How does ATP synthase synthesize ATP?

Answer 53

the electron transport results in the pumping of H+ in the intermembrane space creating a proton gradient (pH gradient and membrane potential); to equalize this, the proton flows back to the matrix via F0 subunit of ATP synthase resulting to its rotation including the internal rod present in the F1 subunit which generates a proton-motive force and conformational change in the F1 subunit allowing the binding of ADP and Pi to form ATP

Question 54

Upon oxidation of NADH in the ETC, how many protons are pumped?

Answer 54

10

Question 55

Upon oxidation of FADH2 in the ETC, how many protons are pumped?

Answer 55

6

Question 56

How many protons are required to synthesize 1 mole of ATP?

Answer 56

4 protons

Question 57

How many ATP can be produced via the oxidation of NADH in the ETC?

Answer 57

10/4 = 2.5 ATPs

Question 58

How many ATP can be produced via the oxidation of FADH2 in the ETC?

Answer 58

6/4 = 1.5 ATPs

Question 59

If 3 NADH are oxidized during ETC, how many ATPs can be produced?

Answer 59

7.5 ATPs

Question 60

In terms of ATP yield via oxidation phosphorylation during ETC, which is more favorable precursor NADH or FADH2?

Answer 60

NADH, generate 2.5 ATPs

Question 61

Inhibitors or ETC and the the transport process they inhibi

Answer 61

CI (NADH Dehydrogenase) to CoQ (Ubiquinone) Rotenone Amytal Piericidin Antimycin A - CoQ (Ubiquinone) to CII (Succinate CoQ Oxidoreductase) CIV (Cytochrome C Oxidase) to O2 Cyanide (CN-) Carbon Monoxide (CO) Azide (N3-)

Question 62

Why rotenone is poisonous to fish and insects?

Answer 62

It blocks the electron transport chain from CI (NADH dehydrogenase) to CoQ (ubiquinone) resulting to ATP shortage and energy failure leading to death

Question 63

How does rotenone inhibits the ETC?

Answer 63

it blocks e- transfer between CI and CoQ

Question 64

Would the oxidative phosphorylation of FADH2 proceed normally in the presence of rotenone?

Answer 64

Yes, FADH2 enters ETC at CII via CoQ hence not affected by rotenone which only inhibits e- transfer from CI to CoQ

Question 65

What cofactor should be utilized as precursor compound for the ETC to proceed normally in the presence of Amytal?

Answer 65

FADH2

Question 66

a barbiturate sedative

Answer 66

Amytal

Question 67

Piericidin is what type of material/substance?

Answer 67

an antibiotic

Question 68

How does Amytal works as a sedative agent?

Answer 68

It inhibits e- transfer from CI to CoQ decreasing or halting the production of ATP leading to sedation

Question 69

Can piericidin inhibit the normal production of ATP under FADH2 precursor?

Answer 69

No

Question 70

Draw the structure of rotenone

Question 71

Draw the structure of amytal

Question 72

Draw the structure of piericidin

Question 73

Draw the structure of Antimycin A

Question 74

an antibiotic that inhibits the transfer of e- from CoQ to Complex III

Answer 74

Antimycin A

Question 75

In the presence of rotenone, how many ATP can be produced from the oxidation of NADH?

Answer 75

4/4 = 1 ATP

Question 76

In the presence of piericidin, how many ATP can be produced from the oxidation of FADH2?

Answer 76

6/4 = 1.5 ATP

Question 77

In the presence of Antimycin A, how many ATP can be produced from the oxidative phosphorylation of FADH2?

Answer 77

0, FADH2 will not be oxidized

Question 78

If you subject a cell to an to an antimycin A antibiotic, would the cell still produce ATP from oxidative phosphorylation of NADH and FADH2 or ETC?

Answer 78

yes, only 1 ATP from NADH in complex 1

Question 79

If you subject a cell to an to an antimycin A antibiotic, how many ATP can the cell produce from oxidative phosphorylation of NADH and FADH2 or ETC?

Answer 79

1 ATP

Question 80

How does CN-, CO, and N3- inhibit ETC?

Answer 80

block the e- transfer from CIV (cytochrome c oxidase) to O2 (final electron acceptor)

Question 81

Terminal ETC inhibitors

Answer 81

Cyanide (Cn-), Carbon Monoxide (Co), Azide (N3-)

Question 82

Is ATP synthase an ATPase enzyme?

Answer 82

Yes, ATPase is a group of enzymes that catalyze either the synthesis or hydrolysis of ATP

Question 83

Inhibitors of ATPase

Answer 83

Oligomycin Dicyclohexylcarbodiimide (DCCD)

Question 84

What are the most dangerous ETC inhibitors? And why are they considered most dangerous inhibitors?

Answer 84

CN-, CO, N3- Because neither of NADH and FADH2 can produce ATP via ETC

Question 85

An antibiotic/ anti-fungal agent that inhibit the function of ATPase

Answer 85

Oligomycin

Question 86

Draw the structure of Oligomycin

Question 87

Draw the structure of Dicyclohexylcarbodiimide (DCCD)

Answer 87

Dicyclohexylcarbodiimide (DCCD)

Question 88

How do ATPase inhibitors affect the synthesis of ATP via ETC?

Answer 88

they prevent the influx of protons from intermembrane space to mitochondrial matrix through ATP synthase which causes the ETC and ATP synthesis to stop since no Proton-motive force will be generated

Question 89

What will happen to the ETC of actively respiring mitochondria upon exposure to the ATPase inhibitors?

Answer 89

ETC ceases to operate

Question 90

Can mitochondria still generate proton-motive force when exposed to oligomycin?

Answer 90

No, proton influx is prevented

Question 91

Uncouplers of ETC and OP

Answer 91

2,4-dinitrophenol Thermogenin

Question 92

What ATP synthase subunit is affected the most when a cellular mitochondria is exposed to Dicyclohexylcarbodiimide (DCCD)?

Answer 92

F0 subunit since proton influx is prevented

Question 93

How does uncoupling of ETC and OP affect the production of ATP?

Answer 93

proton motive force is dissipated as heat and no ATP is generated

Question 94

Will the electron transport from NADH/FADH2 to O2 proceeds normally in the presence of acidic aromatic compounds?

Answer 94

Yes, but PMF is dissipated as heat not as ATP

Question 95

Will uncouplers affect the transfer of electron from NADH/FADH2 to O2?

Answer 95

NO, only the ATP synthesis is affected

Question 96

In the presence of 2,4-Dinitrophenol, will the increased consumption of O2 and NADH/FADH2 oxidation results in the increase of energy captured as ATP?

Answer 96

No, only increase in energy as heat

Question 97

Why was the use of 2,4-dinitrophenol as a slimming/weight loss drug stopped?

Answer 97

Because it can cause death since energy produce via ETC or Op is only in the form of heat but not as ATP

Question 98

How does 2,4-Dinitrophenol prevent the production of energy as ATP?

Answer 98

2,4-Dinitrophenol is acidic due to the presence of nitro group in the phenol ring which is protonated in the mitochondrial intermembrane space (acidic); they are also hydrophobic due to their phenol ring which allows them to easily penetrate the also hydrophobic inner mitochondrial membrane while carrying the H+ (protons); and since mitochondrial matrix is alkaline, 2,4-dinitrophenol will be easily deprotonated releasing the proton inside the membrane without the need of ATP synthase causing the generation of energy in the form of hea

Question 99

Is 2,4-dinitrophenol protonated or deprotonated inside the mitochondrial matrix?

Answer 99

Deprotonated

Question 100

uncoupling protein in the brown tissue mitochondrion (brown fat)

Answer 100

Thermogenin

Question 101

Where are brown fats located in an infant?

Answer 101

back, neck, and shoulders

Question 102

How does thermogenin generate heat?

Answer 102

by "short circuiting" the mitochondrion proton battery

Question 103

How does thermogenin prevent the production of ATP via ETC or OP?

Answer 103

They provide a separate channels where protons directly enters and generate heat without the need for ATP synthase

Question 104

Why thermogenin is highly important in infants?

Answer 104

to keep them warm, prevents hypothermia