Oxidative Phosporylation // Electron Transport Chain Flashcards
What is oxidative phosphorylation?
ATP is formed as a result of transfer of electrons from NADH or FADH to 02 by a series of electron carriers.
How many of the ATP molecules are generated from complete oxidation of glucose to CO2 and H20?
26 out of the 30 ATP molecules were generated from complete oxidation.
Why is the release of energy from the oxidation of FADH2 and NADH important?
This is important as it powered the production of ATP.
What is the electron transport chain?
A series of membrane protein complexes in the inner membrane couple electron transport to H+ movement.
What is the electron transport chain also known as?
The chemiosmotic part of the pathway.
Explain what is a proton motive force.
This is when H+ ions are pumped from the matrix into the intermembrane space.
So is an electrochemical gradient of protons across a membrane.
What does the proton motive force do?
The proton motive force powers ATP synthase and therefore, generates ATP.
What are the 2 components which drive H+ in the same direction?
Chemical gradient = changes pH
Electrical gradient = changes electrical voltage
What is the electron transport chain made of?
It’s made of 4 membrane protein complexes called I - IV.
What is the Complex I NADH dehydrogenase?
It is an enzyme which is supposed to take off the two electrons off from NADH.
What is Complex I also known as?
- NADH dehydrogenase
- NADH - Q oxidoreductase
How many core subunits are essential and conserved in all species?
There are 14 core subunits.
What are the 2 domains in Complex I?
- Hydrophhilic Domain
- Membrane Domain
Explain the membrane domain.
Does not contain redox centres.
Pumps 4 H+ across membrane per 2e- donated by NADH.
Explain the hydrophilic domain.
Contain redox cofactors.
NADH is oxidised to NAD+
The 2e- are passed to ubiquinone (Q) forming ubiquinol (QH2) at the membrane.
What is Complex II?
It is an enzyme of the citric acid cycle.
Complex II’s enzyme is succinate dehydrogenase.
What is Complex III (bc1 complex)?
Membrane contains a hoard of ubiquinol (QH2) which is reduced in Complex I and II.
Explain the mechanism of Q cycle.
This is a cycle involving Complex III.
Complex III passes electrons from QH2 to another electron carrier known as cytochrome C.
4H+ ions are pumped across membrane as 2 electrons are passed from QH2 to CYT C.
What are electron carriers used for?
Electron carriers are a way of moving electrons through the system.
What is cytochrome C’s purpose?
Transfers the electrons from Complex III to Complex IV.
Explain the basic traits of Cytochrome C.
Small and water soluble protein.
It’s found in intermembrane space of mitochondria.
Contains a haem cofactor too.
Where is the ATP synthase normally found?
Found in mitochondria // chloroplasts in eukaryotes.
How does ATP synthase work?
Uses energy from proton motive force to drive ATP synthesis.
Can also use ATP hydrolysis to generate a proton motive force.
The proton flow through ATP synthase leading to the production of ATP.
What is the evidence for the rotation of the ATP synthase?
The F1 part of a bacterial ATP synthase was attached to a. solid surface and a fluorescent actin filament attached to the y subunit.
ATP was added to drive the enzyme in the backwards direction.
