L17- Oxidative phosphorylation

Question 1

What is made in the citric acid cycle that is then oxidized in oxidative phosphorylation?

Answer 1

NADH and ubiquinol (QH2)

Question 2

What is formed in oxidative phosphorylation when they are oxidized?

Answer 2

NADH and ubiquinol (QH2)

Question 3

What happens in summary in the ETC?

Answer 3

Oxidation energy is used to transport protons, creating a proton gradient.

Question 4

What does ATP synthase use?

Answer 4

The proton gradient energy produce ATP

Question 5

When do glycolysis and citric acid cycle happen?

Answer 5

Glycolysis- cytoplasm

Citric acid cycle- matrix of mitochondria

(apart from the one enzyme in the membrane)

Question 6

Where is the movement of protons?

Answer 6

Across the inner membrane

Question 7

What must the inner membrane be so that we can generate energy?

Answer 7

Impermeable by protons and intact

Question 8

What happens to the pH inside the mitochondria as the ETC happens?

Answer 8

The pH rises as H+ (protons) get transported out

Question 9

What’s created across the inner membrane?

Answer 9

A small charge difference, as +ve charge is being transported out

Question 10

How many complexes are in the ETC?

Answer 10

4 Electron transport complexes I-IV. Then ATP synthase at the end.

Question 11

Who came up with the chemiosmotic theory? what is it?

Answer 11

Electron transfer is coupled to proton movement across a membrane. Gradient buils up and sevres as an energy reservois during ATP formation.

Peter Mitchell in the 1960s

Question 12

Which experiment convinces peter mitchell?

Answer 12

O2 was only consumed when ADP was added. When 24-DNP was added, it could move protons across the membrane, so didn;t need ATP

Question 13

WHat is protonmotive force? (∆p)

Answer 13

The energy (driving potential) of the proton conc. gradient.

Question 14

In the negative E’ (v) side of the ETC, what is favourable and unfavourable?

Answer 14

Conversion of NADH to form NAD+. Extraction of elctrons. Reduction is unfavourable.

Question 15

Which reaction is favoured at the +ve E’ (v) side?

Answer 15

Conversion of O2 and H+ to water is favourable

Question 16

Which complex in the ETC is involved in the citric acid cycle?

Answer 16

Only complex II!!!

succinate-ubiquinone oxidoreductase. converting succinae to fumarate

Question 17

What can ubiquinone bind to?

Answer 17

The first 3 complexes in the ETC chain

Question 18

What redox does ubiquinone do with the complexes?

Answer 18

It accepts electrons from the first 2 complexes. It gives electrons to complex III.

Question 19

What are the mobile electron carriers?

Answer 19

Cytochrome C and ubiquinone

Question 20

WHere does cytochrome C accept or donate its electrons?

Answer 20

When bound to complex III it accepts electrons.

When bound to complex IV, it donates electrons

Question 21

Where do the elctrons come from at the start of the ETC?

Answer 21

Either NADH and succinate

Question 22

WHat happens to flavin coenzymes in the ETC?

Answer 22

They’re reduced.

In complex I- FMN–> FMNH2

complex II- FAD —> FADH2

Then they give electron one at a time to the mobile coenzymes

Question 23

How many electrons needed to convert ubiquinone (Q) to ubiquinol (QH2)?

Answer 23

2 electrons

Question 24

HOw many protons are translocated per 2 electrons transferred?

(in complex I)

Answer 24

4 H+ per 2 electrons

Question 25

What does complex II do?

Answer 25

Complex II does not contribute to proton gradient, but supplies electrons from succinate

Question 26

WHere’s FAD? What does it do with its electrons?

Answer 26

FAD is attached to complex II. Then transfers electrons one at a time to ubiquinone. Q–> QH2

Question 27

WHen ubiquinol gets to complex III, what does it do?

Answer 27

GIves its electrons to complex 3. QH2–> Q

Question 28

complex 3 whats the movement of H+?

Answer 28

4 H+ are translocated, two from the matrix and two from QH2.

Same ratio as complex I

Question 29

Where do electrons go from complex 3?

Answer 29

Electrons transferred to cytochrome C located in the intermediate space.

Question 30

WHat’s the ratio of H+ to electron in complex IV?

Answer 30

One proton for every electron