Oxidative Phosphorylation Flashcards
What is oxidative phosphorylation?
High energy electrons (carried by NADH and FADH2) are used to reduce O2 to H2O
Their energy is used to pump protons (H+) from the mitochondrial matrix to the intermembrane space, what happens to the protons after this?
Protons flow back across the membrane, following thier conc. gradient
Energy of proton flow is used to phosphorylate ADP to ATP
What happens to the electron flow in the respiratory chain?
Flow down the ECC from negative to more positive redox potential
What happens to big jumps in redox potential?
Equates to big changes in G. These chnages in free energy can be harnessed
How many mitochondria exist in liver cells?
1000-2000
What two stages are there in oxidative phosphorylation?
Electron transport and ATP synthesis
What happens in the electron transport?
- Electron flow from NADH and FADH2 to O2
- Respiratory chain
- Energy is used to pump H+ out of the mitochondrial matrix
What happens in ATP synthesis?
- Electrochemical gradient of H+ across mitochondrial inner membrane
- Energy stored in this gradient can be used to synthesise ATP
How is the electron transport and ATP synthesis catalysed?
Separate proton pumps
How many multisubunit complexes are ther ein the ECC?
4
What occurs within these 4 complexes in the ECC?
Electrons from NADH enter at complex 1
Electrons from FADH2 enter at complex 2
Electrons are handed down from higher to lower redox potentials
Is complex 2 in the ECC a proton pump?
No
What step that occurs in the ECC causes us to breathe?
electrons are ultimately transferred onto O2 to form H2O
Is Cytochrome c soluble?
Yes
More protons are in the intermembrane space than in the membrane what does this lead to?
Forms an electrical field with the matrix side more negative
Meaning protons want to flow back into the matrix
What is the flow of electrons back into the matrix coupled with?
ATP synthesis
What is ATP synthase also called?
Mitochondral ATPase
F1F0ATPase
Where does the F1 subunit protrude into?
The mitochondrial matrix
Where is the F0 subunit located?
Hydrophobic complex in the inner membrane
-contains the proton channel
What do conformational changes in the ATP synthase pump lead to?
ATP synthesis
What happens when the protons flow through the ATP subunit?
they rotate
What two components exist within the ATP synthase subunit?
Rotating component
Static component
What is the P/O ratio?
How is it calculated?
A measurement of the coupling of ATP synthesis to electron transport
Number of molecules of the inorganuc phosphate (Pi) incorporate into ATP per atom of oxygen reduced
What is the P/O ratio for NADH when oxidised to NAD+ AND FADH2 when oxidised to FAD
NADH- 2.5
FADH2- 1.5
How many cycles does the TCA cycle run?
2
OXPHOS diseases is a common egenerative disease that is due to what?
Mutations in the mitochondrial or nuclear DNA caused by oxidative phophorylation
Where does OXPHOS disease occur and why does pathology become worse with age?
Appears in tissues with highest ATP demands- nervous sytem, heart, skeletal muscle, kidney
With age, spontaneous mutations accumulate, at some point not enough ATP can be generated
