Glycogen, TCA Cycle and Mitochondria (Lecture 12) Flashcards
outer mitochondrial membrane
porous, ions diffuse
phospholipid synthesis
inner mitochondrial membrane
invaginations increase the surface area.
impermeable to ion transport and other molecules
ETC
oxidative phosphoryaltion
mitochondrial matrix
PDC CAC Glutamate DH FA oxidation urea cycle replication transcription/ translation
what is oxidative phosphorylation?
protein complexes take e- from NADH and FADH2. the free energy released by the e- is coupled to the transfer of protons from the matrix to the inner membrane space
H+ is pumped by complex I, III, IV complex II (succinate dehydrogenase) doesn't pump out H+ the reentry of the H+ from the inter membrane space to the matrix is coupled too the rotational torque of ATP synthase to generate energy
why is H+ pumped into the inter membrane space?
generate an electrochemical gradient, a proton motive force
the ETC transports e- form ____ to _____ potential
low potential to high potential
what is special about complex II?
does not pump protons into the matrix
it is invoiced in the CAC
what are the redox centers (prosthetic groups) to accept and release electrons? and which complexes are they associated to?
complex I and II are known as flavo proteins, because they contain flavo mono-nucleotide (FMN) and flavin adenine di-nucleotide (FAD) respectively
complex III (and 2) contain cytochromes which functions to accept and release electrons
purpose of iron sulphur (Fe-S) centres?
pass along the electrons
the sulphur in the cysteine residues will bid to iron, and Theron gains/loses electrons
what is coenzyme Q
e- carrier that is extremely hydrophobic, thus it can diffuse within the mitochondria trial membrane
both electrons form compels I and II feed into coenzyme Q
it will give the e- to complex III
what is cytochrome C
hydrophobic carrier to carry e- to complex IV
cytochrome are complexes to metals to allow for the accepting or release of e-
where does O2 get reduced?
after H+ have passed complex IV, where it is reduced to H2O
4 e-
electron path in the ETC
in complex I, NADH will reduce electrons and pass it to FMN–> Fe-S
OR
succiante carries electrons to FAD–> Fe-S –> cytochrome
coenzyme Q will travel in the mitochondrial membrane to deliver e-
in complex III, e- will be accepted and released by cytochromes coupled to Fe-S
cytochrome C will carry e-
in complex IV, e- will be accepted and released by Cooper (Cu) and cytochromes. eventually, O2 is reduced to water
proton motive force is identified by complex V (ATP synthase), which generates ATP
Complex I
NADH -Coenzyme Q reductase
main donor of e- is NADH
the e- will travel down the FMN, iron sulphur centre
e- will reduce coenzyme Q
2 functions of complex I
- catalyses the transfer of 2 e- from NADH to FMN, which then transfers e- to the Fe-S clusters 1 at a time (this oxidized NADH)
- transfer of 4 H+ into the inner membrane space (reduction of CoQ drives this)
e- transfer causes a conformational change in the transmembrane arm (perpendicular to other proteins) , which supports proton pumping . this back and forth perpendicular movement of th protein, will open/shut the H+ channel
proton translocation channel
in complex I
the anti porter like subunits are linked to the distant Q site
when e- enters the coenzyme Q, its reduced and coenzyme Q is negatively charged
this causes a conformational change in the Q site , which is transmitted to the H channels via the long helical arm of Nqo12
complex II
coenzyme Q reductase
does not pump H
succinate from the CAC will get oxidized by succinate DH and the e- form succiante will enter the complex
the pathways to reduce coenzyme Q
- complex 1
- complex 2
- ETF can receive e- form FAD or dehydrogenase. ETF is then oxidized by ETF-QO. this oxidization will transfer the e- form ETF onto CoQ. this occurs in the matrix
- glycerol-3-phosphate dehydrogenase oxidizes G3P –> DHAP in the cytosol . the e- are donated to FAD and in turn donated to CoQ
complex III
complex III catalyses the reduction of 2 molecules of cytochrome C. it does this by oxidizing coenzyme Q
coenzyme Q can accept 2e-, vat cytochrome C can only accept 1. therefore there a complex cycle to account for this stoichiometry : Q cycle
the Q cycle
Q= coenzyme Q = ubiquinone
QH = semi ubiquinone
QH2 = ubiquinol
- fully reduced coenzyme Q, QH2, wil bind to the Qo site. the protons will be transported to the inter membrane space, but cytochrome c can only accept 1 e-.
- 1 electron will be sued to reduce cytochrome C, the second electron is put only Q to make QH
- QH2 binds, 2 H+ go to the inter membrane space, 1 e- reduced cytochrome c and the other will now take QH to make a fully reduced QH2
2 ubiquinol molecules are fully oxidized to Q, only is fully reduced to form QH2, 2 cytochrome c molecules have been fully reduced
complex IV
catalyses the transfer of 4 e- from 4 reduced cytochrome c molecules to generate 2H2O
every 2e- donated from NADH will cause 10 H+ pumped
respirasome
the etc subunits aggregate together to form a super complex
this is done for efficiency (of e- transfer like channeling) or for the reduction of byproducts (RO species) or to limit the crystallization of complexes
lower reduction potential implies
that the molecule is more likely to give up e-
higher reduction potential implies
that the molecule is more likely to accept an electron
shuttling cytosolic NADH to the mitochondria
cytosolic NADH cannot go into the mitochondria via the cytosol, this it must be put on shuttles
- Glycerol 3 phosphate shuttl.
transfers cytosolic NADH by putting these e- onto DHAP to make G3P which can pass the membrane. the e- will then be put onto FADH2 to generate DHAP . DHAP will diffuse back into the cytosol
- malate/aspartarte shuttle.
e- put onto oxaloacetate to make malate (reverse in CAC). malate holds onto the electrons of NADH and can come into the mitochondrial matrix. malate eis oxidized to release the electron onto NADH. oxaloacetate is generated, but it cannot diffuse, thus it will undergo a transamination reaction with glutamate to generate aspartic acid and alpha KG , once out of the mitochondria the reverse transamination reaction will occur to make glutamate and oxaloacetate.
Fo ring contains ___ rings, which allows for ___ H+ to pass per subunit. This will generate ___ ATP per turn.
8 rings
1H+/ subunit
3 ATP/ turn
how do we calculate the P/O ratio?
to make ATP , Pi is needed to phosphorylate ADP. the import of Pi is done by the importation of a H+ (no electrical disturbances)
we add this extra H+ per ATP (+ 3H) –> 8H+ + 3 H+= 11H+ to make 3 ATP
11/3 = 3.7 protons per ATP
for every 2e- donated to oxygen in the respiratory chain, 10 H+ pumped (complex 1 = 4H+and complex 3/4 = 6H+)
or 6H+ via complex 2
final division
10H+ (equivalent to Oxygen)/3.7 H+ per ATP = 2.7
6H+ (equivalent to Oxygen)/3.7 H+ per ATP = 1.5
