Oxidative Phosphorylation Flashcards
Where are electrons from reduced fuels transferred to?
NADH
FADH2
What does the pyruvate dehydrogenase complex do?
Converts to pyruvate to Acetyl CoA
Where is pyruvate dehydrogenase found?
In the matrix
What is found on the inner membrane?
Respiratory electron carriers (Complexes I - IV)
ATP synthase
What is needed for ATP synthesis?
Proton gradient
Explain the chemiosmotic theory.
Reduced substrate donates an electron
Electron carriers pump protons out as electrons flow towards O2
Energy of electron flow is stored as electrochemical potential
ATP synthase uses electrochemical potential to synthesise ATP
What name is given to complex I?
NADH hydrogenase
What name is given to complex II?
Succinate hydrogenase
What name is given to complex III?
Cytochrome c oxidoreductase
What name is given to complex IV?
Cytochrome oxidase
What are cytochromes?
Iron coordinating porphyrin ring derivatives
How many electrons does cytochrome carry?
1 electron
What are Iron-sulfur centres coordinated by?
Cysteine in proteins
What does ubiquinone donate to ubiquinol?
2 electrons and 2 protons
What is the role of ubiquinol?
Carries electrons with protons across the membrane
What is ubiquinone?
Electron transporter from Complex I and Complex II to Complex III
What is the cofactor that enters Complex I?
NADH
What accepts electrons from NADH and how many?
FMN accepts 2 electrons
How do electrons reach the ubiquinone binding site?
By passing one at a time to iron-sulfur centres
What complexes are proton pumps in the electron transport chain?
NADH hydrogenase
Cytochrome c oxidoreductase
Cytochrome oxidase
How many electrons are carried by ubiquinone to complex III?
2
How many protons are pumped into the intermembrane space by Complex I per NADH?
4 protons
What does ubiquinone become once reduced?
QH2
What is the role of succinate hydrogenase in the electron transport chain?
Capture and donate electrons
What enters Complex II, carrying electrons?
FADH2
How many Fe-S centres are in succinate hydrogenase?
3
What do the 2 electrons carried by Coenzyme Q do?
Reduce 2 molecules of cytochrome c
Do both electrons directly enter complex III from ubiquinone?
No, one enter and one is recycled and may enter later
How many electrons may cytochrome c carry?
1
How many protons are pumped per 2 electrons that reach cytochrome c?
4
What does ubiquinone move through?
The membrane
What does cytochrome c move through?
The intermembrane space
What cellular process is regulated by cytochrome c?
Apoptosis
What does cytochrome oxidase contain molecularly?
2 haeme groups - a and a3
Cu ions
What does Cu a do in complex IV?
2 ions that accept electrons from cytochrome c
What does Cu b do in Complex IV?
Its bonded to haeme a3, forming binuclear centre that transfers 4 electrons to oxygen
How many subunits does complex IV have?
13
What are the 4 electrons passed into Complex IV used for?
Reduces oxygen into 2 water molecules
What happens during the process involving 4 electrons in Complex IV?
4 protons are picked up from the matrix used to form the water as well as moving into intermembrane space
What is the equation from complex I to complex IV?
NADH + 11H+ + 1/2O2 -> NAD+ + 10H+ + H2O
What is the equation from complex II to complex IV?
FADH2 + 6H+ + 1/2 O2 -> FAD + 6H+ + H2O
How did the proteins create the Proton-Motive Force?
Actively transporting protons across the membrane (I & IV)
Chemically removing protons from the matrix (reduction of QH2 and O2)
Releasing protons into the intermembrane space (oxidation of QH2)
What does the proton-motive force do?
Drive ATP synthesis
What does proton translocation cause?
Rotation of Fo subunit and central shaft gamma
What does the rotation of the Fo subunit in ATP synthase do?
Promotes the condensation of ADP and Pi into ATP
What uncouples ATP synthesis from the electron transport chain to generate heat in hibernating animals and babies?
Uncoupling protein 1
