10: Ox Phos Flashcards
Three goals of ox phos
- Transfer electrons from NADH and FADH2 -> O2
- Establish proton gradient across inner mito membrane
- Synthesize ATP
Standard redox potential (Eo’)
Affinity for electrons (inversely proportional to delta G)
Chemiosmotic theory
Electron transfer through respiratory chain leads to pumping of H from matrix to inner-mito space
Proton motive force (pmf) two components
PH gradient, membrane potential
What generates most ATP in the cell?
Oxphos
Three main sources of NADH
- TCA
- Pyruvate dehydrogenase
- Ketone body oxidation
Three main sources of FADH2
- Complex II
- Glycerol phosphate shuttle
- FaCoA dehydrogenase
Which respiratory chain complex is not coded by any mito DNA?
Complex II
What treatment can overcome rotenone poisoning?
Vitamin K3 (menadione)
Side affects of nucleoside analogue treatments like AZT, AraC, and ddC
Fatigue, lactic acidosis, myopathy, cardiac dysfunction, hepatic failure
F0 and F1 subunits of ATP synthase
F0: membrane-spanning channel
F1: where ATP synthesis occurs
Forming 1 ATP requires passage of how many H ions?
3
Uncoupling of respiratory chain
H ions leak through UCP1 (thermogenin), disrupting proton gradient -> energy released as heat
How is thermogenesis in brown tissue started
Brain senses cold -> symp stimulation to brown adipose -> TAGs broken into FAs -> FAs activate UCP1
Common mitochondrial free radical
Ubiquinone radical (partially reduced ubiquinone during e transfer)
What do superoxide dismutases do?
Catalyze O2 superoxide + 2H _> O2 + H2O
SOD1
Cu/Zn SOD; cytosolic
SOD2
Mn/Zn SOD; mitochondrial
What enzyme catalyzes hydrogen peroxide into O2 and water?
Catalase
Name three common antioxidants
Glutathione, vitamin E, vitamin C
Cytochrome P450 superfamily
An e- transport system in the ER that uses NADPH
How does hypoxia in MIs cause lactic acidosis?
Lack of O2 -> decreased respiratory chian activity -> cells depend on glycolysis for energy -> lactic acidosis
First discovered mito disease
Luft’s disease
Luft’s disease symptoms
Perspiration, marked fluid intake with normal urine volume high caloric intake, weakness
Primary and secondary causes of mitochondrial diseases
Primary: defect in DNA (mito or nuclear)
Secondary: ischemia, perfusion, CV disease, renal failure, drugs, aging, alcohol, smoking, etc.
