Photophosphylation Flashcards
Photophosphorylation
The molecular mechanism of transforming light energy to biological energy
Purple nonsulfur bacterium is what?
Cereibacter sphaeroides
What kinds of energy metabolisms does C. spaeroides use?
Aerobic respiration
anaerobic respiration
Phototrophy
What do light harvesting complexes 1 and 2 (LH-1 and LH-2) do?
They are pigment/protein complexes that contain protein bound bacteriochlorophylls and carotenoids that absorb light and transfer the light energy to the reaction center
Where does C. sphaeroides do phototrophy?
Chromatophores
What does the reaction center do?
Contains the special bacteriochlorophyll pair (P870) which are excited from energy from LH1 and LH2. This causes ohotooxidation and an electron is transferred to ubiquinone. The electron hole is filled by an electron from Cyt C. Reduced ubiquinone = ubiquinol which leaves the reaction center
Cytochrome C is where?
P-side = inside reaction center
What is P870?
The reaction center special pair
How does light affect E0’ of the reaction center?
Reduces the E0’ so the electron can leave the RC
Which Q is the reduced one?
Ubiquinol
Which Q is the oxidized one?
Ubiquinone
What’s the semiquinone state?
Where ubiquinone carries one electron and a radical
What’s the electron carrying cofactor of cytochromes?
Heme
Electron transport phosphorylation
The exergonic transfer of electrons from ubiquinol back to Cty C (ubiquinol:cytochrome C oxidoreductase (Cyt bc1 complex)) leads to a proton motive force across the membrane
What enzyme transfers the electron from ubiquinol back to Cty C?
Ubiquinol:cytochrome c oxidoreductase (cytochrome bc1 complex)
