The Electron Transport Chain Flashcards
explain how the electrons travel to the mitochondria
the reduced substrates donate E. Then E carriers pump out H+, and E flow to O2. The energy of E flow is stored as ECP energy. ATP synthase uses this energy to synthesize ATP
what divides the matrix from the outer membrane?
a highly folded, protein rich inner membrane
what is needed to transfer ADP and P into the mito?
transport proteins
list the physical characteristics of the mito?
outer membrane, intermembrane space, inner membrane, cristae, matrix
where are porins and what are its functions?
on the outer membrane, it permits free diffusion
what can pass through the inner membrane freely?
CO2, H20, O2
what needs transport proteins to move through the inner membrane?
ATP, ADP, P, CA2+, pyruvate
where does ATP join onto the ATP-ADP translocator?
there is a positively charged cavity that binds ATP, note that inhibitors ( atractyloside, carboxyatractyloside)
ATR and CATR can act where?
on the external surface of the inner membrane
where does BA (bongkrekic acid) act?
only on the internal surface of the inner membrane
the transfer of electrons from NADH to O2 releases how much energy?
2.5 ATP
how are electrons passed into/onto the mitochondrial membrane?
there are E carries here that allow passage of E from complex I and II, via coenzyme Q to complex III, and then via cytochrome C to complex IV
what is the shape of complex I? How does it transfer electrons?
it is L-shaped. It transfers E form NADH to CoQ via iron-sulfur clusters and sends 4 H+ to the intermembrane space.
how does complex II work?
it transfers E from succinate to the CoQ
how does complex III work?
the E are transferred to cytochrome C, and 4H+ for every 2 E transferred are sent to the intermembrane space. (by the Q cycle)
how does complex IV work?
it accepts E from cytochrome C to reduce O2 to H20 and, sends 2 H+ for every 2 E transferred.
what is the overall delta G of the reaction?
-218kJ/mol
high values of E mean?
a strong tendency to be reduced
complex I is inhibited by?
rotenone, amytal
complex III is inhibited by?
antimycin A
complex IV is inhibited by?
CN-
explain the structures of complex I
it has a membrane arm, an series of iron sulfur complexes, and FMN that has 3 oxidation states. It has a peripheral arm in the matrix side
what are the 3 oxidative states of FMN
FMN—fully oxidized (quinone)
FMNH— partially reduced (semiquinone)
FMNH2—fully reduced (hydroqinone)
coenzyme Q also has 3 oxidative states name them
coQ–fully oxidized
QH+–semi reduced
QH2–fully reduced
where is the transfer of the electron from complex I to coQ
at the N-2
what happens when the electrons meet the peripheral arm?
there are conformational changes in it that induce conformational changes into the transmembrane arm that signal the opening of proton channels in the membrane. Allowing the passage of 4 H+ to the intermembrane space
Complex II is also called
Succinate dehydrogenase or succinate-coenzyme Q oxireductase
Where is complex II and how does it transport electrons
It is embedded in the mitochondrial membrane. It has a series of redox centers present, including a final heme-b cytochrome redox center. Electrons are released from succinate to coenzyme Q. Note that complex II also has FAD which delivers electrons to the iron sulfur clusters. Glycerol 3 phosphate delivers electrons to FAD (then they enter the intermembrane space.) It can also get electrons from the Electron Transporting Flavo Protein
What are cytochromes. Name then and their general structures
They are electron transporting heme proteins .
Heme A : has isoprenoid units attached by an ethyl link, and a covalent hydrophilic bond with the membrane.
Heme C: is the same as A but has a covalent bond with a protein in the intermembrane
Heme B : is iron-protoporphyrin IX
Read slide 36, 45, 47, 48
Dunno how to question it
Complex III is also called
Coenzyme Q- cytochrome C oxireductase
How does complex III work.
It takes electrons from coenzyme Q and send them to cytochrome C, it us redox centers like cytochrome and heme b/l. And it uses the Q cycle. Go to notes for explanation on Q cycle
Explain the structure of cytochrome c
It has a central heme C group, surrounded by positively charged Lys residues. This ring of Lys residues is responsible for holding the heme C in place and helping it interact with the E bus
Complex IV is also called. Explain its components
Cytochrome C oxireductase. It is copper A, B And heme A redox centers. The heme A and copper B are binuclear redox centers. This is where the O2 binding happens. Note that the redox center can only use 3 E
How many O2 do we need to make a H20
2
