Exam 2 Lecture 21 Regulation of OxPhos Flashcards
in regulation of OxPhos, e-s flows from the molecules with _ E0’ to that with the _ E0’
flow from molecules with lower E0’ to that with the highest E0’
E0’ = standard redox potential
what are the 2 factors that govern the pmf to drive ATP synthesis by Complex V
- chemical/pH gradient ( protons are responsible for low pH)
- charge gradient/membrane potential (need intact, non-leaky mem for pos charge)
peter mitchell suggested the chemiosomotic hypothesis to propose what:
proposed that e- transport and ATP synthesis are coupled by a proton gradient across the inner mitochondrial membrane
what are the details peter mitchell’s proposed model?
the transfer of e-s through the respiratory chain leads to pumping of H+s from the matrix to the cytoplasmic side of the inner mito mem. The H+ conc becomes lower in the matrix, creating a neg field in the matrix, and H+s flow back into matrix to equalize
the inner mito mem is _ to H+ and OH- ions
impermeable to these ions so the pmf can be established
ATP synthase/Complex V is embedded in the inner mito membrane.
The F0 subunit is for:
The F1 subunit is for:
F0 unit spans the inner mito mem and contains a proton channel
F1 unit protrudes into the mito matrix and contains the catalytic activity of the synthase
the 5 subunits of F1, which ones have a specific purpose?
alpha and beta subunits bind nucleotides (ATP/ADP) but only beta is catalytically active; the gamma subunit breaks symmetry of the a3B3 hexamer
the formation of the cristae allows:
the proton gradient to be in close proximity to ATP synthase for ehancement of ATP synthesis
1 mole of ATP requires:
3 + 1 H+ passage
the role of the proton gradient is not to form ATP but to:
release it from the synthase
oligomycin does what?
disrupts proton transport through the channel
4 protons enter through the intermembrane space and _n are used
3 are used
ATP and ADP are not permeable across mitochondrial mem thus needs _
a carrier ie ATP-ADP translocase family
The flow of ATP and ADP is coupled which means:
ADP enters the matrix only if ATP leaves
Reduced NADH cannot cross the mitochondrial membrane, thus what are the 2 shuttle systems?
- malate-aspartate shuttle (Complex I)
2. glycerophosphate shuttle (CoQ)
malate-aspartate shuttle operates in:
heart, liver, and kidneys
malate-aspartate shuttle generates NADH in _
in mito-matrix
in the malate-aspartate shuttle, NADH enters to ETC at _
complex I
glycerophosphate-shuttle operates in:
skeletal muscle and brain
glycerophosphate-shuttle generates FADH2 in the _
inner mito-membrane
in the glycerophosphate-shuttle, FADH2 joins to ETC at _
CoQ
levels of _ regulate respiration
ATP
T/F: e-s flow through ETC only when ADP phosphorylated to ATP
true; e-s do not flow through the ETC to O2 unless ADP is simultaneously phosphorylated to ATP
regulation of ADP levels is called:
respiratory control or acceptor control ex when ADP conc rises in active muscle the rate of OxPhos rises to meet ATP needs of the muscle
Inhibition of OxPhos happens when:
when transfer of e-s is inhibited ie:
- a decr in the pumping of protons
- a decr in the proton gradient
- inhibition of ATP synthesis
uncoupling OxPhos from ATP synthesis to generate heat happens in _
brown adipose tissue
in brown adipose tissue, the inner mito-membrane contain uncoupling protein:
UCP 1 aka thermogenin
thermogenin transfers protons from to where?
transports protons from the cytoplasm to the matrix with the assistance of FAs
cytoplasm -> intermembrane space -> matrix
about _ molecules of ATP are formed when glucose is completely oxidized to CO2
30
Most of the ATP, _ of 30 molecules formed when glucose is oxidized to CO2, is generated by OxPhos
26 from OxPhos
thermogenin generates heat by permitting the influx of protons into the mitochondria without _
the synthesis of ATP
Iron-sulfur centers
- Present in complex I, II, III (covalently attached)
- Fe-S centers are non-heme acceptors/donors of e-s
- diseases associated w defects in biogenesis of Fe-S centers
