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52 Cards in this Set

  • Front
  • Back
What reduced cofactors yield most of the energy in the mitochondria?
How many ATP does an FADH2 molecule form?
Where in the cell is ATPase found?
The inner mitochondrial membrane
In which direction are H+ pumped? Into or out of the mitochondrial matrix?
Out, into the inter-membrane space.
What type of gradient is set up by proton pumps? Electric or chemical?
Trick question. Both are utilized as an electrochemical gradient.
Which domain of ATPase is anchored in the inner mitochondrial membrane?
Fo domain
What subunit composes the ATPase "camshaft" and by how much does it rotate with the passage of a proton?
the ϒ subunit, 120 degrees.
How many protons are required to synthesize one molecule of ATP?
3 must go through ATPase, but a total of 4 must be translocated into the matrix (one for Pi)
What moves ATP out into the cytosol and ADP into the matrix?
the ATP-ADP translocator (exchanger)
What is translocated into the matrix along with Pi?
What is the final electron acceptor?
What is ΔE°' and what does it measure?
The change in standard reduction potential, it measures the electron affinity of a molecule.
What has the higher propensity for giving up electrons, NADH or O2? Is its E° positive or negative?
NADH and negative, the more positive E°, the more it "wants" electrons (think positive attracts negative)
What has a higher ΔE°' when donating electrons to O2, FADH2 or NADH? Is this value positive or negative? What about ΔG°'?
NADH, negative, and also negative (thermodynamically favorable)
What characteristic electron carriers do ETC proteins contain?
flavin nucleotides, hemes, iron-sulfur clusters, and copper centers
How many electrons can iron move at a time? What carrier accommodates for this?
1. flavin nucleotides can move one or two electrons at a time.
How are electrons physically carried in the ETC?
Ubiquinone (CoQ) and cytochrome c (they're mobile)
How many electrons can a ubiquinone transfer?
1 (as a semiquinone) or 2 (hydroquinone)
Is ubiquinone hydrophobic or hydrophilic? Cytochrome C?
ubiquinone is hydrophobic and resides within the inner mitochindrial membrane. cytochrome c is hydrophilic and is on the surface of the membrane.
What is the name of Complex 2?
Succinate Dehydrogenase (the only TCA cycle protein)
What ETC complexes pump H+?
Complexes 1, 3 & 4
How many hydrogen atoms are pumped into the matrix by the transport of 2 electrons through complex 1?
What role does glycerol-phosphate dehydrogenase play in the ETC?
It can take the place of succinate dehydrogenase (complex 2) in donating electrons via the oxidation of FADH2
From what proteins can ubiquinone accept electrons?
complex 1, succinate dehydrogenase, glycerol-phosphate dehydrogenase, and fatty acyl-CoA dehydrogenase.
What is the name for complex 3?
cytochrome reductase
Why do are flavins worth less energy than NADH?
They skip complex 1, yielding 2 fewer H+ pumped per electron
What carries electrons between complexes 3 and 4?
cytochrome c
What is the substrate for cytochrome oxidase?
cytochrome c is the substrate for complex 4 (aka cytochrome oxidase)
How many H+ are pumped by the passage of 2 electrons through complex 3? Complex 4?
4 by complex 3, 2 by complex 4
Starting with NADH, how many protons can be pumped by the ETC? How about FADH2?
10 from NADH, 6 from FADH2
Through what must NADH give up its electrons to before they're passed on to iron centers?
FMN because NADH can only give up 2 electrons at a time, whereas iron centers can only accept them one at a time
Percentage-wise, about how efficient is oxidative phosphorylation?
50% (the rest is lost as heat)
How do electrons transfer from complex 2 to complex 3?
What is the final center in complex 4 that donates electrons to oxygen?
cytochrome A3 copper B binuclear electron center
inhibits complex 1, an insecticide from plants
inhibits complex 1, a barbiturate
inhibits complex 3, an antibiotic
inhibits complex 4
Everything downstream of an inhibited complex will be reduced or oxidized?
Will ubiquinone be oxidized or reduced with the addition of antimycin?
How is malate a source of electrons for NADH?
malate dehydrogenase -> OAA -> NADH
What happens when succinate is supplied to rotenone-treated cells? Cyanide-treated?
succinate will add electrons to the ETC via complex 2, so a cell treated with rotenone (inhibits complex 1) will survive whereas cyanide (inhibits complex 4) will not
What processes can become uncoupled?
transfer of electrons and ATP synthesis
When does ATPase become active and collapse the proton gradient?
When there is a high concentration of its respiratory regulator, ADP
What causes the ETC to start pumping protons?
when the H+ gradient is collapsed
What is brown adipose?
contains thermogenin, a H+ channel which collapses the H+ gradient and releases energy in the form of heat, bypassing ATPase
Are electrons being transferred when oxidative phosphorylation is uncoupled
Yes, because the H+ concentration is being collapsed
What four things are required for ATP synthesis (other than basic cellular machinery)?
electron donor, O2, ADP and Pi
What is at a physiological higher concentration, ADP or Pi?
Pi, which is why ADP is the respiration regulator
inhibits the H+ channel in ATPase
an uncoupler, it can be protonated in the inner mitochondrial space and diffuses through the lipid bilayer (b/c it's nonpolar) and then deprotonates in the mitochondrial matrix, effectively collapsing the H+ gradient
Is O2 consumed in an uncoupled ETC?
Yes because electron transport is functioning to restore the collapsed H+ gradient