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25 Cards in this Set
- Front
- Back
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What's the general process for Chemoorganotrophs? |
Glucose + oxygen--> carbon dioxide + water |
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What's the general process for chemolithotrophs? |
H2 + oxygen--> water |
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What are the 2 types of phototrophy? |
1. use Rhodopsins containing retinal (photoheterotrophs only) 2. have photosynthetic reaction centers that contain bacteriochlorophyll (photoautotrophs & some photoheterotrophs) |
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what 2 sets of rxns do photoautotrophs perform? |
1. light rxns: light energy conserved as chemical energy and reducing power 2. Dark rxns: Chemical energy and reducing power used to reduce carbon dioxide to organic compounds (otherwise known as carbon fization) |
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What type of rxn is photosynthesis? |
a biological redox rxn in which carbon dioxide is the e- acceptor |
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what's the e- donor in oxygenic photsynthesis? |
water! plants, algae, and cyanobacteria perform this photosynthesis Light creates proton gradient for ATP synthesis |
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whats the e- donor in anoxygenic photsynthesis? |
H2S or So! Purple bacteria, green sulfur bacteria, and heliobacteria perform this photsynthesis Light creates proton gradient for ATP synthesis |
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Chlorophyll a used by algae, plants, and cyanobacteria |
Bacteriochlorophyll used by anoxygenic phototrophs |
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what are the 2 types of membrane bound chlorophyll based reactions centers? |
1. PS I: 1st stable e- center is FeS cluster 2. PS II: quinone is 1st stable e- acceptor oxygenic photosynthesis uses both PS I & PS II |
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What are 4 principles of photosynthetic e- transport? |
1. Light excites chlorophyll-> lowers reduction potential -> can reduce intermediate e- acceptor 2. e- flow downhill w/ increasingly positive dEo' 3. e- trasnport coupled w/ proton trans. to make PMF 4. when 1st e- acceptor has dEo' > NAD+, reverse e- flow is required to make NADH |
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What happens in cyclic e- flow? (PMF generated) |
e- is passed through series of aceptors until it comes back to original pigment that released it. Protons are pumped out during e- transfer near the Q pool to cyt bc1 e- donor such as H2S helps w/ reducing original pigment |
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purple bacteria vs. green sulfur bacteria vs. heliobacteria |
Purple bacteria: 1st stable e- acceptor= Q pool (reverse e- flow ensues) Green sulfur bacteria: 1st stable e- acceptor=FeS cluster (directly reduced Fd for C fixation) Heliobacteria: 1st stable e- acceptor =FeS cluster (Directly reduced Fd for C fixation) |
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What does Oxygenic photsynthesis use? |
A combination of Q-type RC & Fe/S type RC Z scheme: | |\PSI PSII P680 excited (PSII)--> P680*-->drops to P700 (PSI)-->P700 excited-->P700*--> drops down to make NADH |
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What exactly does noncylic phosphorylation do? |
E- on Fd can travel to flavoprotein which reduces NAD+ to NADH generates both PMF and reducing power |
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What exactly does cyclic phosphorylation do? |
e- on Fd can return cyt bf & travel back thru PS1 using more light energy generates PMF only! No NADH/NADPH |
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how is oxidized P700 returned to ground state? What about P680? |
P700--> by e- from plastocyanin P680--> by e- from split water molecules |
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Where is the photsynthetic process found in bacteria? In eukaryotes? |
Bacteria: Located in cytoplasmic membrane or other internal membrane systems Eukaryotes: thylakoid membranes |
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What are thylakoid membranes and who sues them? |
Cyanobacteria they're sheet-like invaginations of the cytoplasmic membrane. where photosystem complexes are held |
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What are chlorosomes and who uses them? |
Green sulfur bacteria They're large clear areas near the cytoplasmic membrane |
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What are RCs surrounded by? |
Light harvesting complexes. They recieve light energy & pass it quickly to RC Looks kinda like a flow w/ everything flowing inwards |
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what happens in RC? |
charge seperation and e- transport occur here |
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What are 3 classes of light- harvesting pigments? |
1. Chlorophylls 2. Phycobilins- 3. Carotenoids- light harvesting& photoprotection |
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What is the absorption spectra of chlorophylls? |
range from as low as UV to as high as IR |
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What are carotenoids? |
always found in phototrophic organisms absorb blue light, but they're yellow, red, brown, or pink Transfer energy to RC & they're anti-oxidants (anti-oxidants= photoprotection) |
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What are phycobilins? |
Light- harvesting complexes Found in cyanobacteria Mainly red & blue pigments *spectra: UV & IR |
