Oxidative Phosphorylation Flashcards
Where does Ox Phos occur?
In the inner membrane of mitochondria
Where does TCA and fatty acid oxidation occur?
In the matrix of the mitochondria
What three components make up successful Ox Phos?
- transfer electrons from NADH and FADH2 to O2
- Establish proton gradient across inner membrane mitochondria
- Synthesize ATP
What complexes pass electrons from NADH to O2?
NADH Q oxidoreductase (complex I) Q cytochrom c oxidoreductase Complex III Cytochrome C oxidase Complex IV Called the Respirasome Flow of E- across inner membrane
What are the mobile electron carriers?
Coenzyme Q aka Ubiquinone which transfers electrons from C1 to CII to CIII
Cytochrome C which shuffles electrons from Q cytochrome C oxidored. (CIII) to Cytochrome C oxidase (CIV)
What is another name for complex one?
NADH Dehydrogenase or NADH-Q Oxidoreductase
First point of entry and both nuclear and mito genes
What is another name for complex two and what enters ETC through it?
Succinate-Q reductase and FADH2 enters it connects krebbs to oxphos. DOESN’T pump protons so less ATP from ox of FADH2
What is another name for complex III?
Cytochorme C oxidoreductase where electeons from QH2 are passes to cytochrome c. Moves 2 protons to the cytoplasmic side
What is another name for complex four?
Cytochrome C Oxidase. transfers electrons from reduced Cyt. C to molecular oxygen
What is the final electron carrier?
oxygen
What are examples of ROS?
Superoxide ion, peroxide ion, and hydroxyl radical from the partial reducction of oxygen
Five Antioxidants?
SOD Catalase Glutathione peroxidase Vit. E Vit. C
Describe the flow of electrons in the gradient?
Flows from molecules with lower Eo’ highest Eo’
What leads to the pumping of H ions from matrix to IMS?
Electron transfer through respiratory chain
What two factors make up the Proton motive force to drive ATP synthesis by Complex V?
pH gradient and membrane potential
What are the three postulates of the chemiosmotic theory?
- ETC translocates protons across IMS across the complexes
- ATP synthase uses proton motive force to drive phosphorylation of ADP
- Inner membrane is impermeable to H and OH ions, if cant be disrupted a pmf cant be established and ATP synthesis doesn’t occur
What is another name for complex V?
ATP Synthase
Describe structure of ATP synthase?
Ball and Stick structure
Fo subunit is stick embedded in the membrane with a proton channel anad the F1 subunit is a ball that protrudes into matrix side and contains catalytic domains
How are the alpha and beta F1 subunits arranged?
alternately in a hexameric ring both bind nucleotides but only the beta are catalytically active
What allows the proton gradient to be in close proximity to ATP synthase?
The Cristae
What disrupts proton transport through the channel in ATP synthesis?
Oligomycin
Are ATP/ADP permeable across mitochondrial membrabe?
No they need a carrier, an ATP-ADP translocase family which resides in the outer and inner mito membranes and works with mito carriers
How does ATP and ADP flow into and out of matrix?
ADP enters matrix only if ATP leaves it. Known as complex 6
What are the two shuttle systems for reduced NADH to cross mito. membrane?
Malate aspartate shuttle and Glycerophosphate shuttle
Where is the malate aspartate shuttle found?
Heart liver and kidneys and it generates NADH in mitochondrial matrix and NADH enters ETC at complex I
Where is the glycerophosphate shuttle found?
Skeletal muscle and brain. It generates FADH2 in the inner mitochondrial membrane FADH2 joins ETC at CoQ
How do levels of ATP regulate respiration?
Electrons only flow through the ETC when ADP is phosphorylated to ATP.
What is regulation by ADP called?
Respiratory control or acceptor control
What happens if Oxphos is inhibited?
Decrease in pumping of protons and a decrease in the protein gradient and inhibition of ATP synthesis because there is no PMF
In hibernating animals where does the uncoupling of oxphohs from ATP synthesis to generate heat occur?
in brown adipose tissue
How does uncoupilng and heat generation occur?
Inner mito membrane contains uncoupling protein UCP1 aka thermogenin which transfers protons from IMS to matrix. Energy converted to heat instead of ATP. UCP 2 and 3 also uncouple oxphos from ATP synthesis.
