L17- Oxidative phosphorylation Flashcards Preview

Biochemistry > L17- Oxidative phosphorylation > Flashcards

Flashcards in L17- Oxidative phosphorylation Deck (30):

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

NADH and ubiquinol (QH2)


What is formed in oxidative phosphorylation when they are oxidized?

NADH and ubiquinol (QH2)


What happens in summary in the ETC?

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


What does ATP synthase use?

The proton gradient energy produce ATP


When do glycolysis and citric acid cycle happen?

Glycolysis- cytoplasm

Citric acid cycle- matrix of mitochondria 

(apart from the one enzyme in the membrane)


Where is the movement of protons?

Across the inner membrane


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

Impermeable by protons and intact


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

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


What's created across the inner membrane?

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


How many complexes are in the ETC?

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


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

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


Which experiment convinces peter mitchell?

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


WHat is protonmotive force? (∆p)

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


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

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


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

Conversion of O2 and H+ to water is favourable


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

Only complex II!!!

succinate-ubiquinone oxidoreductase. converting succinae to fumarate


What can ubiquinone bind to?

The first 3 complexes in the ETC chain


What redox does ubiquinone do with the complexes?

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



What are the mobile electron carriers?

Cytochrome C and ubiquinone


WHere does cytochrome C accept or donate its electrons?

When bound to complex III it accepts electrons.

When bound to complex IV, it donates electrons


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

Either NADH and succinate


WHat happens to flavin coenzymes in the ETC?

They're reduced.

In complex I- FMN--> FMNH2

complex II- FAD ---> FADH2

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


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

2 electrons


HOw many protons are translocated per 2 electrons transferred?

(in complex I)

4 H+ per 2 electrons


What does complex II do?

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


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

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


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

GIves its electrons to complex 3. QH2--> Q


complex 3 whats the movement of H+?

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

Same ratio as complex I


Where do electrons go from complex 3?

Electrons transferred to cytochrome C located in the intermediate space.


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

One proton for every electron