Bioenergetics pt 2 Flashcards
What are the three goals of ox phos?
To transfer e- from NADH and FADH2 to O2
To establish a proton gradient across the IMM and in the intermembrane space
To synthesize ATP
Describe the flow of e- during oxphos
The e- flows from the molecules with lower standard redox potential (E0’) to that with the highest redox potential (low affinity to high affinity e-)
What two factors contribute to the proton motive force (pmf) to drive ATP synthesis by complex V?
pH gradient (delta pH) and membrane potenital
How many protons are needed for the synthesis of 1 mol ATP?
3+1 H+
What inhibits ATP synthase?
oligomycin
When the transfer of e- is inhibited what occurs?
a decrease in the pumping of protons, a decrease in the proton gradient and inhibitor of ATP synthesis
What regulates Oxphos?
Presence of O2 (no oxygen, no oxphos)
ATP/ADP ratio (high decreases and low activates)
How does a high ATP/ADP ratio influence the TCA cycle and oxphos?
Inhibits ATP synthase, increases [H+] gradient, decrease e- transport and proton pumping, slows down TCA cycle, decreases glycolysis and leads to decreased [ATP]
How does a low ATP/ADP ratio influence the TCA cycle and oxphos?
Activates ATP synthase, decreases [H+] gradient, increases e- transport and proton pumping, accelerates TCA cycle, increases glycolysis and leads to increased [ATP]
Role complex I (NADH dehydrogenase) plays in oxphos
e- transfer facilitated by tightly bound FMN and Fe-S clusters
Accepts 2 e- from NADH and donates them to coenzyme Q
Pumps 4 H+ from the matrix into intermembrane space
Role complex II (succinate dehydrogenase) plays in oxphos
Protein bound to the matrix side of the IMM
e- transfer facilitated by FAD and Fe-S clusters
Transfers 2 e- from FADh2 to coenzyme Q
NO proton pumping
What role does coenzyme Q (ubquinone) play in oxphos?
Mobile - able to move freely within the lipid bilayer of the IMM
Converted to ubiquinol upon acceptance of 2 e- from complex I or II and transfers them to complex III
What role does complex III (cytochrome c reductase) play in oxphos?
e- transfer facilitated by Fe-S clusters and cytochromes b and c1 which harbor Fe-containing heme-b and c molecules
Accepts 2 e- from ubiquinol and donates them to cytochrome c
pumps 2 H+ from matrix into intermembrane space
What role does cytochrome c play in oxphos?
Also mobile
e- transfers facilitated by an iron containing heme c group
Accepts e- from complex III and donates them to complex IV
What role does complex IV (cytochrome c oxidase) play in oxphos?
e- transfer facilaited by Cu centers and cytochromes
Accepts e- from cytochrome c and transfers them to oxygen which forms water
Pumps 4 H+ into intermembrane space