Study Set Content:
When succinate oxidizes to fumarate, 2 electrons are accepted by
FAD
When succinate oxidizes to fumarate, 2 electrons are accepted by FAD within
complex II
FAD passes them to
Fe-S clusters
FAD passes them to Fe-S clusters and then to
coenzyme Q
However; no (blank) are translocated across the membrane by complex II, therefore less ATP is produced with this pathway
protons
•Coenzyme Q, also known as
ubiquinone
•Coenzyme Q, also known as ubiquinone (CoQ), is made up of
quinone and a hydrophobic tail.
Coenzyme Q, also known as ubiquinone (CoQ), is made up of quinone and a hydrophobic tail. Its purpose is to function as an electron carrier and transfer electrons to
complex III
. Coenzyme Q undergoes reduction to
semiquinone
ts purpose is to function as an electron carrier and transfer electrons to complex III. Coenzyme Q undergoes reduction to semiquinone (partially reduced, radical form CoQH-) and
ubiquinol
partially reduced, radical form CoQH-
semiquinone
Fully reduced CoQH2
ubiquinol
oenzyme Q undergoes reduction to semiquinone (partially reduced, radical form CoQH-) and ubiquinol (fully reduced CoQH2) through the
Q cycle
This process receives further elaboration under
Complex III.
Complex III, also known as
cytochrome c reductase
• Complex III, also known as cytochrome c reductase, is made up of
cytochrome b, Rieske subunits (containing two Fe-S clusters), and cytochrome c proteins.
A cytochrome is a protein involved in electron transfer that contains a
heme group
The heme groups alternate between
ferrous and ferric states
Fe2+
ferrous
Fe3+
ferric
