1. Phototrophs Photophosphorylation for ATP generation:
still requires a PMF and ATP synthase,
light as an energy input instead of NADH (or reduced inorganic compound) oxidation.
Photosynthesis (photoautotrophs):
Light Reactions
Cyclic Photophosphorylation (Photosystem I = PSI)
Non-Cyclic Photophosphorylation (Photosystem II = PSII)
Dark Reactions (Calvin Cycle)
Photopigments:
Chlorophylls; carotenoids; phycobiliproteins
Antenna (hundreds of pigment molecules to capture light)
Reaction-center chlorophyll (the link to electron transport)

2. Chlorophylls Cyanobacteria and Eukaryotes have Chlorophyll a
Green and Purple Bacteria have Bacteriochlorophylls
The core is a tetrapyrole ring with a magnesium molecule.

3. Prochloron and eukaryotes
Accessory Pigments
Prochloron and eukaryotes
Eukaryotes alone
Bind with proteins; cyanobacteria & red algae

4. Different phototrophs have different pigments.
Pigments absorb light at unique wavelengths.
Wavelengths of light reaching an environment can be different.
Phototrophs best equipped to absorb available wavelengths in a given environment yield more energy.

5. Cyclic Photophosphorylation (PS I)
Absorbs wavelengths ≥680 nm (P700)

6. Non-Cyclic Phosphorylation (PSII)
Absorbs wavelengths ≤680 nm (P680)

7. Z-scheme
NADP+

10. Green Sulfur Bacteria, Chlorobium
Live in anoxic sulfide rich habitats.
Sº accumulates outside the cell.
Cyclic for ATP or non-cyclic to reduce NAD+.

11. Green Non-Sulfur Bacteria Thermophilic using organic matter for electron donor in photoheterotrphy; H2 for photoautotrophy (e.g. Chloroflexus).

12. Purple Sulfur Bacteria
Live in sulfide rich and anoxic habitats.
Anoxygenic photoautotroph.
So accumulates intracellularly as inclusion bodies.

13. Purple Non-Sulfur, Rhodobacter
Winogradsky
column
Need a supply of organics or H2.
Tolerates O2 or S-2.
Some photoautotrophs.

14. Phototrophy Overview
Purple and Purple Non-Sulfur Bacteria require means of producing reduced electron carriers; done by reverse electron flow, as with chemolithoautotrophs.
(or PMF)

15. Calvin Cycle Carboxylation Phase
Ribulose 1,5-bisphosphate
Fixation of 3 Carbon Dioxide molecules to one molecule of Glyceraldehyde 3-Phosphate (G3P) via carboxylation & reduction requires 3 cycles.
Each cycle requires regeneration of Ribulose 1,5-bisphosphate (RuBP) to fix the next CO2 via the enzyme RuBP Carboxylase.
Regeneration of RuBP from 5 G3Ps follows a reversal of the PPP.
6 cycles will yield 2 G3Ps, which can form a hexose via Gluconeogenesis.
Regeneration Phase
Reduction Phase

16. Anabolism

17. Nutritional Types Revisited