L13-14-Metabolic Diversity Flashcards
Describe the structure and function of bacteriochlorophyll, chlorosomes, and accessory pigments.
- bacteriochlorophyll-in anoxygenic phototrophs, similar to cytochromes but contain magnesium instead of iron, absorb light
- chorosome-prokaryotic specialized structure along long axis of membrane. Capture low intensity light, giant antenna system
- Accessory pigments-work in conjunction with chlorophyll, carotenoids(photoprotection) and phycobilin (light-harvesting)
Describe electron flow in anoxygenic phototrophs.
Exciton energy strikes p870 molecules and excites special pair of electrons to bacteriochlorophyll a. Flow from low E0’ to high E0’: bacteriophytins (bph), quinones, iron sulfur proteins then cytochromes and eventually back to reaction center. Fuels pmf. Electrons are reused/no net consumption like respiration.
What is reverse electron flow?
???electrons travel backwards through ETC powered by pmf. Complex 1 reduces NADH and oxidizes quinone.
Compare and contrast electron flow in oxygenic vs. anoxygenic phototrophs.
Oxygenic-flow through two distinct light systems: photosystem 1 and 2, P700 and P680, chloroplast
Anoxygenic-flow through one system, use of P870, P840, P798 etc., stacks in cytoplasm or chlorosomes
Both-occur in membranes, pairing of electron flow & reduce NAD
Compare the energy yield from different inorganic electronic donors.
Hydrogen, sulfide, and sulfur yield more energy than phosphite, ammonium, nitrite, and ferrous iron
Describe the oxidation of reduced sulfur compounds (fig 13.22a)
x
Describe electron flow during Fe2+ oxidation.
x
Describe iron oxidation under anoxic conditions.
x
Explain how bacteria oxidize ammonia.
x
Explain how nitrifying bacteria oxidize nitrite.
x
Compare and contrast anammox to ammonia oxidation.
x
