ETC Flashcards
How to calculate the respiratory control ratio?
slope of a/slope of b on graph
What is CoQ
lipid-soluble quinone
shape of graph with inhibitor of ETC added, then ADP and DNP
Minimal change in O2 concentration
- ETC cannot function and use O2
What’s an uncoupler?
Disconnects ATP synthase from the rest of the ETC, resulting in the rest of the ETC creating O2 and heat at a much higher rate
Other name of Complex 1
NADH Dehydrogenase
Steps of Complex 1
1) NADH -> NAD transfers 2e- and 2H+ to FMN -> FMNH2
2) e- move to iron of Fe-S then to CoQ
3) energy of e- used to pump 4H+ from matrix to inter membrane space
Other name of Complex II
Succinate Dehydrogenase
Steps of Complex II
1) electrons move from FADH2 to Fe-S then to CoQ
Which complexes pump H+ and what are their non-complex names?
Complexes I, III, IV, V
I: NADH DH
III: QH2-cytochrome c reductase
IV: cytochrome oxidase
V: ATP Synthase
Which carriers deliver electrons to CoQ?
Complex I, Complex II, ACD, GPDHm
Steps of GDPHm
mitochondrial glycerol-3-P DH
moves electrons from cytosolic NADH -> FAD -> FADH2 -> CoQ
Steps of ACD
Acyl-CoA DH
FAD -> FADH2 -> CoQ
Inhibitors of Complex I
Rotenone, Amytal
Inhibitors of Complex III
Antimycin A
Inhibitors of Complex IV
HCN (cyanide), CO, H2S, N3- (azide)
Which complex does CoQ transfer its electrons to?
Complex III (QH2-cytochrome c reductase)
How may H+ pumped across the proton pumps?
10 total
4 Complex I
4 Complex III
2 Complex IV
How do cytochromes change when they carry electrons?
The Fe in their heme ring readily converts from Fe2+ to Fe3+
Role of cytochrome c
Picks up electrons from Complex III and brings them to Complex IV
Other names Complex IV
cytochrome oxidase
Complex IV reaction
reduces O2 to H2O
Structure of ATP synthase
Fo spans inner membrane
F1 sticks into the matrix
- contains C ring
- 3 subunits
Complex V steps
1) H+ enter Fo via proton channel, driving rotation of the c ring
2) c ring rotation causes conformational change in the 3 subunits on Fi
3) one rotation = 3 ATP
Inhibitor of Complex V
Oligomycin
What do the three subunits of Fi do?
1) bind ADP + Pi
2) phosphorylate ADP to ATP
3) release ATP
What do the glycerol phosphate shuttle and malate aspartate shuttles do?
Oxidizes NADH to NAD for reuse in Glycolysis and transports the electrons to FAD in the ETC
(NADH cannot enter the mitochondria)
Glycerol P shuttle mechanism
1) Glycerol-3P DH loads e- and H+ onto DHAP
2) DHAP -> Glycerol-3P -> enters mitochondrial matrix
3) G3P reduces FAD to FADH2
4) G3P becomes DHAP and reenters cytosol
Malate-Aspartate shuttle mechanism
1) Malate DH(cyto) transfers H+ and e- to Oxaloacetate, creating Malate
2) Malate DH(mito) reduces NAD to NADH
3) Malate converted to Oxaloacetate
4) Oxalo. combined with Glutamate to create Aspartate and a-ketoglutarate
5) Aspartate antiport with glutamate
6) a-ketoglutarate antiport with malate
7) recombine into oxalo and glutamate
- this is all because oxaloacetate cannot cross the membrane
Leber Hereditary Optic Neuropathy
- ETC complex subunit mutations
- results in nerve damage in eye bc no disable mitochondrial function
- maternally inherited
Permeability of inner vs outer mitochondrial membranes
Inner: Impermeable to most small ions including H and others
Outer: contains special channels formed by porin protein, permeable to most ions and small molecules
Electron flow from different Eo values
Electrons flow from more negative Eo to more positive Eo
Oxidation of CoQ
CoQ -> 2H+2e- -> QH2
UCP-1 mechanism
Creates pores in IMM, leading to dissolution of H+ gradient
DNP mechanism
Shuttles H+ across IMM, dissipating gradient
