L8 Oxidative phosphorylation

Question 1

What is the function of NADH dehydrogenase (Complex I)?

Answer 1

Transferring electrons from NADH to unbound ubiquinone (Q) to form ubiquinol (QH2)

Question 2

Each Fe is always coordinated by how many S in the Iron-sulfur clusters?

Answer 2

4

Question 3

What is the function of succinate dehydrogenase (Complex II)?

Answer 3

Transferring succinate to fumarate

Question 4

Is there any proton pumping in Succinate dehydrogenase (Complex II) ?

Answer 4

No

Question 5

Which complex is the only membrane -bound enzyme in TCA cycle?

Answer 5

Complex 2: Succinate dehydrogenase

Question 6

What is the function of Cytochrome oxidase (Complex IV)?

Answer 6

Transfers electrons from cytochrome c to oxygen

Question 7

For every 2 electrons donated by NADH, how many ATPs are synthesized?

Answer 7

2.5

Question 8

For every 2 electrons donated by FADH2, how many ATPs are synthesized?

Answer 8

1.5

Question 9

How many electrons NAD+/NADH and NADP+/NADPH carries at a time?

Answer 9

2

Question 10

Is NAD+/NADH and NADP+/NADPH diffusible or bound in enzymes?

Answer 10

Diffusible

Question 11

Is FAD/FADH2 and FMN/FMNH2 diffusible or bound in enzymes?

Answer 11

Bound in enzymes

Question 12

What is the highly folded inner membrane called?

Answer 12

Cristae

Question 13

Where does the electron flow occur?

Answer 13

The inner membran of mitocondria

Question 14

The energy released form the electron transference is used for what process in NADH dehydrogenase (complex I) ?

Answer 14

Proton pumping from the matrix ito intermembrane space

Question 14

What is the initial electron donor of the oxidative phosphorylation?

Answer 14

NADH

Question 15

How many electron and proton can FMN transfer at a time?

Answer 15

1

Question 16

What is the final eletron carrier in complex one?

Answer 16

Q/QH2

Question 17

Are they any energy release in Complex II?

Answer 17

Yes, but really little (-2kJ /mol), not enough to pump the proton

Question 18

What are the electron carriers in Complex III?

Answer 18

Complex III is called cytochrome bc1 complex
(1) Fe-S clusters
(2) Cytochrome b
(3) Cytochrome c1

Question 19

Is cytochrom c water soluble?

Answer 19

Yes

Question 20

What is the main result of the first round in the Q cycle?

Answer 20

QH2 becomes a half-reduced semiquinon (.Q-)

Question 21

WHat are the electron carriers in cytochrome oxidase(complex IV)?

Answer 21

2 Cu ions and 2 heme A groups (cytochrome a proteins)

Question 22

In which complex in the ETC:
O2 is used up and water is generated?

Answer 22

Complex IV
Cytochrome oxidase

Question 23

Oxygen oxidized which molecule in cytochrome oxidase (complex IV)?

Answer 23

cytochrome c

Question 24

How many proton does Complex four pumped out?

Answer 24

2 protons per 2 electrons

Question 25

The energy stored in the gradient, proton-motive force, has two components, what are they?

Answer 25

(1) Chemical potential energy (inside the membrane: alkaline) (2) Electrical potential energy (inside the membrane: negative)

Question 26

What are the two units of ATP synthase?

Answer 26

F0 and F1

Question 27

Protons flow through which unit of ATP synthase?

Answer 27

F0

Question 28

ATP is synthesized by which unit?

Answer 28

F1

Question 29

Why NADH need to have a shuttle system?

Answer 29

Because inner mitochondrial membrane is impermeable to NADH

Question 30

What are the two different shuttle system for NADH?

Answer 30

(1) Glycerol 3-P shuttle system (2) Malate-aspartate shuttle system

Question 31

What does reducing equivalents mean?

Answer 31

Molecules that can be transported into the mitochondria

Question 32

In Glycerol 3-P shuttle system, which electron carrier acts as the reducing equivalents?

Answer 32

FAD/ FADH2

Question 33

In Glycerol 3-P shuttle system, which two complex are skipped?

Answer 33

Comlex one and Complex two

Question 34

Glycerol 3-P shuttle system takes place in which kind of human tissues?

Answer 34

Skeletal muscle and brain

Question 35

Malate-aspartate shuttle system takes place in which kind of human tissues?

Answer 35

Liver, kidney, and heart

Question 36

What is the key enzyme involved in the glycerol 3-P shuttle system?

Answer 36

G-3P dehydrogenase

Question 37

What are the key enzymes involved in the Malate-aspartate shuttle system?

Answer 37

Dicarboxylate translocase adn Glutamate-aspartate translocase

Question 38

What is the main difference between Glycerol 3-P shuttle system and Malate-aspartate shuttle system regarding the involvement of the complex in ETC?

Answer 38

Glycerol 3-P shuttle system involes only III and IV, while Malate-aspartate shuttle system involves I, III and IV