Lecture 25/26: Oxidative Phosphorylation & Regulation Flashcards
In OxPhos, electrons are transferred from what to what
NADH and FADH2 –> O2
Oxidative phosphorylation occurs where
Inner membrane of mitochondira
Which of the complexes in the ETC does not pump protons
Succinate Q reductase (Complex II)
FADH2 enters ETC where and its electrons are transferred where
FADH2 enters through succinate-q reductase (Complex II)
It does not leave the complex
Its electrons are transferred to Coenzyme Q
Which complexes make up the respirasome
Complexes I, III, IV
Coenzyme Q AKA ubiquinone function
Transfers electrons from complexes I and II to complex III
Cytochrome C function
Shuttles electrons from Complex III to Complex IV
Final component of the ETC
Catalyzes reduction of O2
Iron sulfur clusters
Play role in reduction reactions
Undergo oxidation-reduction reactions but the protons never leave the protein
Complex I
NADH-q oxidoreductase or NADH dehydrogenase
First point of entry of electrons from NADH
Protons are pumped to cytoplasmic side
Complex II
Succinate-q reductase
FADH2 enters ETC here
Does not pump protons, therefor less ATP is produced from oxidation of FADH2
Complex III
Cytochrome C oxidoreductase
Electrons from QH2 (reduced coenzyme Q) are passed on to cytochrome C by this complex
2 Protons are pumped to cytoplasmic side
Complex IV
Cytochrome C oxidase
Transfers 4 electrons from reduced Cytochrome C to O2
Protons are pumped to cytoplasmic side
Cytosolic superoxide dismutase vs mitochondrial
Cytosolic- Cu/Zn
Mitochondrial- Mn/Zn
ATP synthase uses energy derived from what to drive phosphorylation of ATP
Proton motive force
Is the inner mitochondrial membrane permeable to H+ and OH ions?
No, if the membrane was permeable, a proton motive force would not be able to be established
Complex V contains F0 and F1 subunits that each have subunits of their own. Which subunit of F1 is catalytically active
only Beta subunits
What allow the proton gradient to be in close proximity to ATP synthase
The cristae
What is complex 6
ATP-ADP translocase family, reside in inner and outer mito-membranes
Flow of ATP/ADP coupled - one in and one out
Malate aspartate shuttle operates in what organs, generates what, and where does it enter the ETC
Operates in the heart, liver and kidneys
Generates NADH which enters ETC at Complex I
Glycerophosphate shuttle operates where, generates what, and where does it enter the ETC
Skeletal muscle and brain
Generates FADH2 which enters ETC at CoQ
What happens when transfer of electrons is inhibited
Decrease in proton pumping
Decrease in protein gradient
Inhibition of ATP synthesis
What is thermogenin AKA UCP-1
Uncoupling protein that uncouples oxphos from ATP synthesis. This is done in brown adipose tissue and is used to generate heat instead of ATP
-Transfers protons from cytoplasmic side to matrix to generate heat
Malonate
Inhibits complex II
What toxins inhibit complex IV
CO
Cyanide
H2S
