The electron transport chain Flashcards
where is NADH synthesized and where can it not go
synthesized in the cytosol and cannot cross the inner mitochondrial membrane
how does NADH get into the inner mitochondrial membrane
transfer electrons via 2 redox reactions
what are the 2 redox reactions that move NADH into the inner mtochondrial membrane
glycerol-3-phosphate shuttle
malate-asparate shuttle
what is the requirement for the malate-asparate shuttle to operate
only operates where cytosolic NADH:NAD+ ratio is higher in cytosol than the mitochondrial matrix)
how many sites of entry are there for the ETC
four
name the four entry points for the ETC
complex 1 for NADH
complex 11 for FADH
complex 111
comples 1V
what is complex 1 for NADH also known as
NADH dehydrogenase or NADH-Q reductase
what is complex
1 for NADH/ NADH dehydrogenase/ NADH Q-Reductase
a flavoprotein containing FMN
name all 3 of the complex 11 enzymes
succinate a-reductase (dehydrogenase)
glycerol-3-phosphate Q10 reductase (also a dehydrogenase)
fatty acyl CoA dehydrogenase
what are all complex 11 enzymes
flavoproteins
what do complex 11 enzymes do
reduce FAD to form FADH2
FADH2 transfers electrons via Fe-S to Coenzyme Q10 (ubiquione)
what is ubiquione
coenzyme Q10
what does ubiquione/ coenzyme Q(10) do
diffuses through membrane
in reduced form (QH2) transfers electrons from complex 1 and 11 to complex 111
what is complex 111 known as
QH2-cytochrome C reductase
or
ubiquione-cytochrome C reductase
what does complex 111/ QH2-cytochrome C reductase/ ubiquione-cytochrome C reductase do
ozidises ubiquinone
reduces cytochrome C
ie transfers electrons from ubiquione to cytochrome C
how does the transfer of electrons in complex 111 occur
via cytochrome b, an iron sulphur complex
and
cytochrome c1
what does cytochrome C do
diffuses through membrane from complex 111 to complex 1V
what is complex 1V also known as
cytochrome C oxidase
what does complex 1V do
oxidises cytochrome C1 and reduces in a sequence cytochrome a, a3 and O2
what is produced from Complex 1V
o2 which is reduced and produces water
what happens if 02 is only partially reduced by complex 1V
oxygen free radicals are produced
what happens to protons during the ETC
pumped out of the matrix into the intermembrane space
forms a proton gradient which drives ATP synthesis by ATpase (ATP synthase)
what is involved in the protons being pumped out of the matrix
complexes 1, 111 and 1V
what is the P:O ratio
the number of ATPs synthesized per oxygen atom (1/2 O2) consumed or H2O produced
what is the P:O ratio for oxidation yielding NADH
3
what is the P:O ratio for oxidation yielding FADH2
2
how is ATP exported from the mitochondria
ATP:ADP translocase moves ADP from cytosol into matrix in exchange for ATP
so ATP produced in mitochondria is moved out to the cytosol
how is the ETC regulated
increase in ATP:ADP ratio reduces oxidative phosphorylation and ETC slows down
consequently NADH:NAD+ ratio increases
knock on inhibition of pyruvate dehydrogenase, B-oxidation and TCA cycle
what is the ETC not tightly coupled with
oxidative phosphorylation
what does UCP-1 do
in infants brown fat forms channels allowing dissipation of protein gradient to bypass ATP synthase - so energy generated during dissipation is converted to heat
what is the pharmaceutical uncoupler called
2,4 dinitrophenol
what does a pharmaceutical uncoupler /2,4 dinitrophenol do
burns more fuel in effort to make ATP
risks with pharmaceutical uncoupler/ 2,4 dinitrophenol
tissues damage due to lack of ATP production
toxic fever
death
