10.3 Electron Transport Chain [HY] Flashcards
How is energy harnessed via ETC?
Proteins in inner membrane transfer electrons from NADH & FADH2.
In a series of oxidation and reductions. NADH is electron donor and Oxygen is acceptor
Where does ETC take place?
Inner mitochondrial membrane
How does the ETC work?
NADH’s electrons are passed from one complex to the next
ETC Complex 1
NADH-CoQ oxidoreductase
Transfer from NADH to CoQ (coenzyme CoQ)
Iron-sulfur cluster to transfer electrons from NADH -> flavin mononucleotide (FMN) -> coenzyme Q (CoQ), forming CoQH2
Four protons moved
ETC Complex 2
Succinate-CoQ oxidoreductase
Transfer from Succinate to CoQ
Iron-sulfur cluster to transfer electrons from succinate -> FAD -> CoQ, forming CoQH2
No proton pumping to contribute to gradient.
ETC Complex 3
CoQH2-cytochrome c oxidoreductase
Transfer from CoQH2 to cytochrome c
Iron–sulfur cluster to transfer electrons from CoQH2 -> heme,
forming cytochrome c as part of the Q cycle.
Q Cycle: 2 electrons moved from CoQH2 (intermembrane space) to CoQ (mitochondrial matrix)
Four protons are moved.
ETC Complex 4
Cytochrome c oxidase
Transfer from Cytochrome c to Oxygen
Cytochromes & Cu2+ to
transfer electrons as hydride ions (H−) from cytochrome c to oxygen, forming water.
Two protons are moved.
How does NADH participate in ETC?
By being shuttled since it can’t cross inner mitochondrial membrane.
NADH to FADH2 shuttle
Glycerol 3-phosphate shuttle
Electrons from NADH to dihydroxyacetone phosphate (DHAP), forming glycerol
3-phosphate.
These electrons are transferred to mitochondrial FAD, forming FADH2.
NADH to NADH Shuttle
Malate–aspartate shuttle
Electrons are transferred from
NADH to oxaloacetate, forming malate.
Malate crosses the
inner mitochondrial membrane and transfer the electrons to
mitochondrial NAD+, forming NADH.
