Lecture 29 - The electron transport chain Flashcards
What is oxidative phosphorylation
It is the coupled process of electron transport through the ETC and the phosphorylation of ADP to ATP by ATP synthase
What couples the two pathways in oxidative phosphorylation
The proton gradient, created by the ETC and used by ATP synthase, couples the two pathways
Where in the mitochondria does the ETC takes place
In the inner mitochondrial membrane, in the mitochondria as it requires oxygen
The location of ETC experiment inside mitochondria
- Treat with strong detergent:
- Solubilise all membranes
- ETC does not work
- ETC in a membrane - Treat with mild detergent:
- Only removes the outer membrane
- ETC still works
- ETC is in the inner membrane
What takes place in the matrix of Mitochondria
- CAC
- B oxidation
- Pyruvate dehydrogenase
What is the role of electron carriers in the ETC
Electron carriers transfer electrons between complexes in the ETC, facilitating redox reactions an proton pumping
what are the Two mobile carriers
- Ubiquinone (UQ) = Coenzyme Q (CoQ)
- Cytochrome C (cyt c)
energy releasing through carriers
As electrons move to carriers with a higher reduction potential (oxygen has the highest reduction potential) energy is released
Where do the reduced coenzymes that feed into the ETC come from
The reduced coenzymes (NADH and FADH2) are produced during glycolysis, pyruvate oxidation and CAC
Electron flow through ETC direction
NADH -> Complex 1 - UQ - Complex 3 - cyt c - Complex 4 - O2
FADH2 -> Complex 2 - UQ - Complex 3 - Cyt c - Complex 4 - O2
What is the result of energy released by electrons moving up their reduction potential in ETC
The energy is used to translocate protons across the inner mitochondrial membrane, building a proton gradient
What happens if the ETC is inhibited
- Stop flow of electrons through the ETC
- No proton gradient formed (No ATP made)
- Build-up of reduced co-enzymes (NADH and FADH2) so no oxidising power for other pathways
At which complex of the ETC is NADH oxidised
NADH is oxidised at complex 1, releasing two electrons into the ETC and pumping four protons across the membrane
At which complex of the ETC is FADH2 oxidised and how many protons are pumped
FADH2 is oxidised at complex II, releasing two electrons but no protons are pumped at this complex
Why is Succinate dehydrogenase SDH enzyme shared between the ETC and the CAC
SDH is part of Complex 2 in the ETC and catalyses the oxidation of succinate in the CAC linking both processes
What reaction occurs at Comples 4 of the ETC
At complex 4 electrons reduce oxygen to form water
What happens if the complex 1 is inhibited by rotenone
Rotenon inhibits electrons transfer from NADH to CoQ, halting electron flow, proton pumping and ATP production from NADH
What happens if complex 4 is inhibited by cyanide
Cyanide prevents electron transfer to oxygen at complex 4, stopping the ETC, proton gradient formation and ATP synthesis
What is the Q cycle in the ETC
The Q cycle refers to the transfer of electrons from CoQ to complex 3, facilitating proton pumping and electron transfer to Cyt C
How does the ETC link to glycolysis and citric acid cycle
The ETC oxidises NADH and FADH2 produced in glycolysis and the citric acid cycle, converting their energy into a proton gradient for ATP synthesis.
