oxidative phosphorylation Flashcards
what 2 purposes do catabolic pathways serve?
1) breakdown of larger molecules
2) release and temporary storage of high energy molecules (ATP/reduced cofactors)
what kinds of molecules are used to generate ATP?
re-oxidation of cofactors
what is oxidative phosphorylation?
2 separate but connected processes
1) oxidation of reduced cofactors (NADH,FADH2)
2) phosphorylation of ADP to ATP
where does oxidative phosphorylation occur?
mitochondrial membrane
what is the purpose of cofactors in oxidative phosphorylation?
they play a role in reversible oxidation/reduction during electron transport
how do electrons move between cofactors?
they move from cofactors with lower reduction potential to higher reduction potential
-each cofactor has a characteristic reduction potential/affinity for electrons
what are important cofactors in oxidative phosphorylation?
what is FMN?
flavin mononucleotide
-prosthetic group that gets reduced to FMNH2
what are cytochromes?
hemoproteins that carry out electron transport
-the redox rxn’s are imperitive to their function within the ETC
what is Coenzyme Q?
lipid-soluble molecule that transports electrons to complex 3 from complexes 1/2
-reduced at complex 1/2
-oxidized at complex 3
what is used to transport protons across the membrane in the ETC? what kind of transport is this?
free energy changes from redox rxn’s
-primary active transport
what does a higher reduction potential indicate?
more negative delta G
what is the pathway of electrons from NADH through the ETC?
NADH → Complex I → Coenzyme Q (Ubiquinone) → Complex III → Cytochrome c → Complex IV → Oxygen (O2)
how many protins are moved out of the matrix for every NADH molecule that is reoxidized?
10 protons
what provides the energy to pump protons in the ETC?
redox rxn’s
what is another name for complex 2?
succinate dehydrogenase
-integral membrane protein
-contains FAD as a prosthetic group
-Catalyzes oxidation of succinate to fumarate as part of the citric acid cycle
-Electrons from succinate are transferred to coenzyme Q
-**No protons are moved across the membrane at Complex II
what is the path of electrons from FADH2?
FADH2 → Coenzyme Q (Ubiquinone) → Complex III → Cytochrome c → Complex IV → Oxygen (O2)
what are the characteristics of the EC gradient created in the ETC?
high pH and more (-) in the matrix
low pH and more (+) in the intermembrane space
what is the function of the ATP synthase?
conversion of ADP to ATP
what 2 portions make up the ATP synthase>
Fo -transmembrane portion that protons pass through
-triggers conformational change in F1
F1- catalytic portion that synthesizes ATP from ADP and Pi
what does the rate of ATP synthesis determine?
proton movement and oxygen consumption
https://www.youtube.com/watch?v=3y1dO4nNaKY
https://www.youtube.com/watch?v=PjdPTY1wHdQ
https://www.youtube.com/watch?v=AigRzfNHCZA
what is the rate of O2 consumption coupled to?
rate of ATP synthesis
how many ATP are generated per 360 degree turn of the central shaft in the ATP synthase?
3 ATP
what is the P:O ratio for NADH and FADH2? what changes P:O ratio?
~2.5 ATP per NADH
~1.5 ATP per FADH2
the ratio may vary with uncoupling
what is the result of low [ADP]?
how is oxidative phosphorylation coupled when there is low energy use?
how is oxidative phosphorylation coupled when there is high energy use?
what is the affect of addition of ADP on O2 consumption?
addition of ADP will synthesize ATP –> increasing O2 consumption
what is the result of uncoupling?
protons are able to enter the matrix without ATP synthesis
-electron transport with reduced synthesis of ATP
What is the effect of an uncoupler on O2 consumption?
O2 consumption increases
-proton gradient dissipates faster and rate of electron transport increases
-rate of reoxidation of reduced electron carriers increases
-rate of rxn’s in citric acid cycle increases
what affet does 2,4-dintrophenol have on the EC gradient?
it dissipates the proton EC gradient so that more energy/ heat is burned
(diet pill in order to increase energy expenditure)
