Electron Transport Train Flashcards
*Understand the structural aspects of the mitochondrial outer and inner membranes as well
as the inter-membrane space. Understand the differential permeabilities.
Outer mitochondrial membrane- PERMEABLE to most small ions and molecules due to channel protein PORIN.
Specifically VDAC channel (voltage dependent anion channel, allows passage of small ions.
Inner membrane space- fold into ridges called CRISTAE, and is IMPERMEABLE to most molecules.
inner membrane- site of ATP synthesis.
(transporter shuttle metabolites across inner membrane)
*Understand the relationship between the electron-transfer potential and the phosphoryl- transfer potential (i.e. Eo' and Go'
Not needed for exam.
*Understand the distinction between a “strong reducing agent” and a “strong oxidizing
agent”.
Strong reducing agent- readily donates electrons, has NEGATIVE Eo (reduction potential)
Strong oxidizing agent- readily accepts electrons, has POSITIVE E0
*Be familiar with the components of the electron-transport chain. Know how electrons are
transported through this system (figure 20.6).
Electrons start flowing from NADH to COMPLEX 1. then to UBIQUINONE (Q) to COMPLEX 3 to CYTOCHROME C, then to COMPLEX 4.
FROM complex 4 electron passed to OXYGEN; oxygen then reduced to water.
*Why are the electrons carried by FADH2 not as energy rich as those carried by NADH? What
is the consequence of this difference?
Electrons carried by FADH2 enter COMPLEX 2 in the ETC, which does not undergo proton pumping (but undergoes electron transfer), so you will have less protons pumped from FADH2.
Consequence less ATP generated by FADH2; so 1 FADH2 molecule generate 1.5 ATP, while in NADH will generate 2.5 ATP.
*Amytal is a barbiturate sedative that inhibits electron flow through Complex I. How would
the addition of amytal to actively respiring mitochondria affect the relative oxidation-
reduction states of the components of the electron-transport chain and the citric acid cycle?
complex 1 reduced. Complex 2, 3, 4- oxidized
CAC-reduced (NOT important for exam).
*What are the roles of superoxide dismutase and catalase in the cell?
protect against ROS Damage. (not important for exam)
what is role of oxidative phosphorylation?
Oxidative phosphorylation- captures energy of high transfer potential electrons to synthesize ATP.
flow of electrons from NADH and FADH2 occur in ETC (or respiratory chain)
exergonic set of oxidation reaction generates a proton gradient(used to power synthesis of ATP)
What two processes combine to form cellular respiration?
citric acid cycle and oxidative phosphorylation.
oxidative phosphorylation occurs in mitochondrial matrix.
how does reduction potential describe flow of electrons?
reduction potential is Electrons flow from lower (negative) to higher charge (positive value)
ex: final acceptor of electrons is O2 which has positive reduction potential.
What happens every time electrons pass through complexes 1, 3, and 4? What makes complex 2 special?
everytime e- pass through complex 1, 3 and 4, protons are pumped into intermembrane space.
Complex 2 is where electrons carried by FADH2 flows to . Electrons in FADH2 go to complex 2 then to ubiquinone, then complex 3 to cytochrome c to complex 4 to oxygen.
Describe the relative mobility of complexes 1, 2 , 3, 4 compared to ubiquinone and cytochrome c.
Complexes 1, 2, 3, and 4 are in a FIXED STATE, as they stay in the same place, and do not really move.
UBIQUINONE and CYTOCHROME C are VERY MOBILE, and move around a lot in membrane.
Describe the ETC.
ETC -series of coupled oxidation reduction reactions
electrons donated by NADH and FADH2 passed to electron carriers in protein complexes.
Carriers include FMN (flavin mononucleotide), iron sulfur proteins, iron in hemes that are embedded protein called cytochrome, mobile e- carrier Coenzyme Q.
What is a respirasome?
Electrons flow within complexes in inner-mitochondrial membrane to generate proton gradient. these complexes (I, III, IV) associated with another in respirasome.
Which three complexes pump protons out of mitochondria and generate proton gradient?
Complex 1, complex 3 and complex 4
succinate q reductase (not proton pump)
