oxidative phosphorylation and electron transport chain

Question 1

which of the following is false about reduced fuels that are used to synthesize ATP in animals:
A. Carbohydrates, lipids, and amino acids are the main reduced fuels for the cell
B. Electrons from reduced fuels are transferred to reduced cofactors NAD or FAD
C. In oxidative phosphorylation, energy from NADH and FADH2 are used to make ATP
D. A and B
E. none of the above

Answer 1

B

Question 2

The coupling of electron transport with ATP synthesis is called ………………………………………

Answer 2

oxidative phosphorylation

Question 3

where does the ETC takes place?

Answer 3

The electron transport chain takes place within the inner membrane of the mitochondria.

Question 4

which statement is correct about mitochondria
A. the outer membrane of the mitochondria relatively is a porous membrane that allows passage of metabolites.
B. the inter membrane space of the mitochondria has a high concentration of protons as well as pH
C. the inner membrane is mainly impermeable to most small ions including protons and small molecules like ATP, ADP, pyruvate.
It has proton gradient across it Location of electron transport chain complexes
D. the Cristae serve to decrease the surface area
E. A & C
F. all accept D

Answer 4

E

Question 5

true or false

the concentration of H+ in the intermembrane is high, while the pH is low

Answer 5

true

Question 6

True and False

the concentration of H+ in the matrix is low as well as the pH level

Answer 6

false

its low in the H+ and high in the pH

Question 7

which of the following is not included in the matrix
A. TCA cycle enzymes
B. fatty acid oxidation enzymes
C. NAD, FAD, ADP, and Pi
D. Mitochondrial ribosomes
E. ion channels 
F. mtDNA and mtRNA

Answer 7

E

there is no ion channels in the matrix!

Question 8

true or false?

coenzyme Q is a protein complex in the inner membrane that helps organize the ETC

Answer 8

false

it is a lipid soluble quinone that helps organize the TCA

Question 9

all of the following are components of ETC except:
A. NADH DEHYDROGENASE
B. SUCCINATE DEHYDROGENASE
C. COENZYME Q or UBIQUIONONE
D. FADH DEHYDROGENASE
E. CYTOCHROMES
F. CYTOCHROME b + CYTOCHROME a+a3

Answer 9

D

its not even there!

Question 10

which of the following is correct about NADH dehydrogenase

A. It has tightly bound coenzyme called Flavin mononucleotide (FMN) and peptide subunits with iron-sulfur centers
B. FMN accepts 2e +2H and becomes FMNH2
C. As electrons flow, they lose energy. This energy is used to pump protons from the matrix to the intermembrane space.
D. A and C
E. all of the above

Answer 10

E

Question 11

which of the following is wrong about succinate dehydrogenase (complex ii):

A. Electrons are generated from succinate dehydrogenase catalyzed oxidation of succinate to fumarate
B. energy is lost and protons are pumped at Complex II to the inter membrane space
C. produces the highest amount of e-
D. none of the above
E. B and C

Answer 11

E
No energy is lost so no protons are pumped at Complex II
and complex ll doesn’t produce the highest amount of e-

Question 12

which of the following is correct about COENZYME Q or UBIQUIONONE

A. Ubiquinone is a lipid-soluble conjugated dicarbonyl compound that easily accepts electrons
B. It accepts 2 electrons and gives 1 electron at a time
C. Upon accepting two electrons, it picks up two NADH molecules to yield ubiquinol
D. Coenzyme Q is a mobile electron carrier transporting electrons from Complexes I and II to Complex III
E. both A and C
F. A, B and D

Answer 12

F

Question 13

true or false

the cytochromes are one electron carriers

Answer 13

true

Question 14

which of the following is correct about cytochrome a+a3 (complex iv)

A. It is also called cytochrome oxidase because it contains Cu and Fe
B. Oxygen is reduced to water
C.4e are required to reduce 1 mole of copper
D.This is the only carrier in which the heme Fe has an available coordination site to react with molecular oxygen
E. all except C
F. A and D

Answer 14

E

4e are required to reduce 1 mole of oxygen

Question 15

Large negative E°are strong reducing agents or reductants so they have strong tendency to …………….. electrons

Answer 15

lose

Question 16

Large positive E°are strong oxidizing agents, oxidants, so they like to ………………….. electrons

Answer 16

accept

Question 17

the following inhibits electron transfer except

A. Amytal
B. Antimycin
C. cytochrome reductase
D. Rotenone

Answer 17

C

Question 18

H+ are not pumped at which complex?

Answer 18

complex 2

Question 19

what is complex v called?

Answer 19

ATP synthase

Question 20

which of the following is wrong about ATP synthase?

A. Multi-subunit enzyme that synthesized ATP using energy of the proton gradient.
B. After protons are pumped to cytosolic site, they re-enter the matrix by passing through proton channel in the Fo.
C. its called also complex iv
D. all of the above
E. only C and B

Answer 20

C

Question 21

who is the British biochemist who was awarded a Nobel prize for chemistry for his discovery of the chemiosmotic mechanism of ATP synthesis?

Answer 21

Peter Mitchell

Question 22

which of the following is correct about chemiosmotic hypothesis?

A. ETC proteins span the inner mitochondrial membrane to enable proton pumping
B. An intact inner mitochondrial membrane is required for oxidative phosphorylation. The inner mitochondrial membrane is impermeable to the diffusion of ions, such as H+, OH-, K+, and Cl- that would destroy the electrochemical gradient.
C. Compounds, such as 2,4 dinitrophenol (DNP) and trifluorocarbonylcyanide phenylhydrazone (FCCP), that dissipate the proton gradient uncouple oxidative phosphorylation from ETS.
D. Manipulations of mitochondria, such as artificially making a proton gradient stimulate ATP synthesis in them.
E. all of the above
F. all except D

Answer 22

E

Question 23

ATP synthase consist of 2 parts

list them:

Answer 23

F0 base

F1 head

Question 24

all of them are correct about ATP synthesis mechanism except

A. the ATP synthesis consist of 3 steps
B. the first step is binding of ADP + Pi (tight)
C. the second step is the catalysis of the formation of ATP (loose)
D. the 3rd step is the release of ATP (open)
E. Each 360 degree rotation of the c ring generates 3 ATPs.
F. all except B
G. all except B and C

Answer 24

G
Binding of ADP + Pi (Loose)
Catalysis of formation of ATP (Tight)

Question 25

the redox of NADH+ H+ at complex l :

Answer 25

electrons go to complex l, four protons pumped from matrix to inter membrane space

Question 26

redox of FADH2 at complex ll:

Answer 26

coenzyme Q picks up electrons (from complex I and ll ) and transport to complex lll

Question 27

redox of complex lll:

Answer 27

four protons are pumped out from the matrix to the inter membrane space, carrier C transports electrons to complex lv

Question 28

redox of complex iv:

Answer 28

two protons are pumped out from the matrix to the inter membrane space, formation of H2O (20% of water in body)

Question 29

ATP synthase action:

Answer 29

pumps protons from inter membrane space to matrix, produces ATP from ADP + Pi + energy

Question 30

The most efficient generation of ATP by cells occurs when ……………….. and ……………………………….. are ‘tightly coupled.

Answer 30

ETC / oxidative phosphorylation

Question 31

when we rest, [ATP] build high —> a lack of ADP in the mitochondrion —> stoppage of complex V —> stoppage of ETS
Stoppage of complex V —> [NADH] and [FADH2] to rise —> TCA cycle to slow or stop
As the citric acid cycle slows —> acetyl-CoA and citrate accumulate —> ……………………………

what is the result?

Answer 31

lead to synthesis of fat.

Question 32

Oxygen is the terminal electron acceptor. When oxygen is abundant, ETS and complex V can function (if there is sufficient ADP), but if we exercise faster than oxygen can be delivered, we go …………………………

Answer 32

anaerobic.

Question 33

When we go anaerobic —> ETS stops —> rapid dissipation of the proton gradient —> stoppage of oxidative phosphorylation —> [NADH] and [FADH2] to rise —> ……………………………

Answer 33

formation of lactate increase.

Question 34

Remember that ………………. is needed for glycolysis, so it is for this reason that our cells make lactate - to regenerate …………………. because the ETS is stopped.

Answer 34

NAD / NAD+

Question 35

which of the following are chemicals inhibiting synthase?

A. oligomycin
B. Antimycin
C. Rotenone
D. Dicyclohexylcarbodiimide
E. all except D
F. A and D

Answer 35

F

Question 36

The antibiotic ………………………….. inhibits ATP synthase by binding one of F0’s subunits and preventing H+ transport through F0.

……………………………… a lipid soluble compound also inhibits H+ transport through F0.

Answer 36

oligomycin

Dicyclohexylcarbodiimide (DCCD)

Question 37

which of the following is correct about uncoupling of Oxidative Phosphorylation

A. Oxidative phosphorylation is usually tightly coupled to electron transport.
B. It is possible to “uncouple” these two processes, using agents that permeabilize the inner mitochondrial membrane to protons or by biological uncoupling proteins
C. Uncoupling the ETS from oxidative phosphorylation lowers metabolism, and generates heat.
D. There are biological and synthetic uncouplers
E. all except C
F. A and B

Answer 37

E

Uncoupling the ETS from oxidative phosphorylation speeds metabolism, and generates heat

Question 38

which is wrong about biological couplers?

A. UCPs occur in the inner mitochondrial membrane of mammals and they form channels that allow H+s to reenter to matrix without energy being captured as ATP.
B. The energy is released as heat and the process is called shivering thermogenesis
C. UCP1 (aka thermogenin) is responsible for heat production in the brown adipocytes of mammals, not a major role in human except newborn
D. all of the above

Answer 38

B

The energy is released as heat and the process is called nonshivering thermogenesis

Question 39

which of the following is correct about synthetic uncouplers

A. They pick up H+s in the intermembrane space and release them in the matrix, which results in dissipating the gradient
B. 2,4 dinitrophenol (DNP) and carbonylcyanide-p- trifluoromethoxyphenylhydrazone (FCCP) are the two examples
C. High doses of aspirin and other salicylates uncouple OSPHOS, explaining high fever accompanies toxic overdoses of these drugs.
D. Energy is released as heat
E. Uncontrolled uncoupling the ETS system from oxidative phosphorylation is potentially lethal
F. all of the above

Answer 39

F

Question 40

which of the following is wrong about Membrane Transport Systems

A. NADH from glycolysis (cytosolic) must be moved into the mitochondrial matrix
B. Mitochondrial metabolites, such as pyruvate and FADH must be moved out of the mitochondrial matrix.
C. ATP must be moved out of the mitochondrial matrix and ADP and Pi must be moved in.
D. all of the above
E. all except c

Answer 40

B

Mitochondrial metabolites, such as oxaloacetate and acetyl-CoA must be moved out of the mitochondrial matrix.

Question 41

which of the following is correct about Malate Aspartate Shuttle

A. The malate aspartate shuttle uses an enzyme malate dehydrogenase to reduce oxaloacetate to malate
B. This process produces NADH
C. It yields 2.5 ATP (NADH)
D. all of the above

Answer 41

D

Question 42

which of the following is correct about ATP and ADP transport:

A. ATP and ADP do not freely diffuse across the mitochondrial membrane.
B. They too must be shuttled and ADP/ATP antiporter is the shuttle for this process
C. As it imports one ADP from cytosol to matrix, one ATP is exported from matrix to cytosol
D. all of the above

Answer 42

D