lecture 32 - the electron transport chain Flashcards
what is the coupled process of oxidation phosphorylation
- electron transported through the electron transport chain (ETC)
and
- the phosphorylation of ADP to ATP-synthase
they are coupled by a proton gradient
what are the main points of the electron transport chain
- electrons are passed through a series of carriers
- electrons from NADH and FADH2 are fed into chain (they are oxidised)
- these will reduce oxygen to water
- protons are pumped as electrons are transported through the ECT
- builds a proton gradient
what is feed into the electron transport chain
electrons from NADH and FADH2
what is the terminal acceptor in the electron transport chain
oxygen
- will be reduced to water
where does the electron transport chain take place and what does it require
in the inner membrane of the mitochondria = requires oxygen
what is necessaryb to build a proton gradient in the electron transport chain
the inner membrane (barrier)
what are the two mobile carriers of the electron transport chain
- ubiquinone
- cytochrome
what occurs at each carrier through the electron transport chain
redox reactions
- each carrier accepts electrons (is reduced) in one redox reaction
- then donates electrons (is oxidised) in another redox reaction
what happens as electrons move through the electron transport chain
energy is released
what part of the mitochondria has higher H+
the inter-membrane space
what part of the mitochondria has lower H+
the matrix
what are the two possible flow of electrons through the ETC
NADH > Complex 1 > UQ > Complex III > Cyt c > Complex IV > O2
or
FADH2 > Complex II > UQ > Complex III > Cyt c > Complex IV > O2
what does Rotenone inhibit in the ETC
inhibits electron transfer from Complex I to Co-Q (UQ)
what does Cyanide do in the ETC
binds to carrier in Complex IV
what does carbon monoxide do in the ETC
binds where O2 binds
what are the effects of inhibitors of the electron transport chain
- stop flow of electrons through the ETC
- no proton gradient formed (ATP not made)
- build up of reduced co-enzymes (NADH and FADH2) means no oxidising power for other pathways
what occurs at Complex I of the ETC
- NADH is oxidised
- two e- released into the ETC
- four protons are pumped for each NADH oxidised
what occurs at Complex II of the ETC
- FADH2 is oxidised
- SDH reaction is shared citric acid cycle
- two electrons released into the ETC
- no protons are pumped
how many electrons do Complex I and Complex II both pass to UQ / CoQ
they both pass two electrons
where can UQ move
within the inner mitochondrial membrane
Co-Q / UQ releases how many electrons at a time to Complex III
one electron at a time
what are the two forms that the mobile carrier UQ / CoQ exists in
= CoQ (UQ) oxidised quinone form, not carrying hydrogen
= CoQH2 (UQH2) reduced quinone form, carrying hydrogen
how redox reactions does CoQ / UQ undergo and how many electrons can it release or accept at one time
- two redox reactions
- but can accept or release one electron at a time
what occurs at Complex III of the electron transport chain
- Complex III releases one electron at a time to Cytochrome c
- Complex III pumps four protons across the inner membrane
where can cytochrome c move in the ETC
moves on the outer surface of the inner mitochondria membrane
what does cytochrome c do
carries one electron at a time from Complex III to Complex IV
what occurs at Complex IV
accepts one electron at a time from cytochrome c
- reduces oxygen to water
biologically what will Complex IV wait until
it will wait until it has four electrons (O2 + 4H+ > 2H20)
