Bits of Photsynthesis Plant Physiology Biology UNI 2008

Plant job description light H2OH2O CO 2 sugar O2O2 The good stuff?

CH 2 OPP CHO O HO COOH OH O HO O O OH HO OH O O HO OH CHO CH 2 OH COOH GGP P Phytoene  -carotene Lycopene  -carotene Zeaxanthin Violaxanthin Astaxanthin Xanthoxin ABA Retinal Retinol Retinoic Acid synthase desaturase cyclase hydroxylase epoxidase ketola se dioxygenase CH 2 OPP IPP  -carotene hydroxylase Lutein

Chlorophyll fluorescence dumps excess energy from absorbed light Blue light shined on this green tissue, red fluorescence from chlorophyll.

Photosystem geometry Light harvesting complex = Rxn center + Antenna pigs Reaction center Antenna Pigments

Shade and sun plants Sun plant Shade plant Genetic control (capacity) and developmental control. May not be able to adjust later.

Photosynthetic electron flow ADP + Pi ATP H+H+ H+H+ H+H+ 3 H + NADPH PS IIPS I H 2 O split H2OH2O O2O2 Water splitting complex Cytochrome complex Thylakoid membrane Coupling factor e-e- e-e- e-e- e-e-

The PQ “pump” - + from PS II to PS I interior of thylakoid stroma thylakoid membrane PQ: plastoquinone Used electron power to move protons (charge battery)

Balanced photosynthesis PhotoSynthesis High energy compounds Harvests light energy Uses harvested energy Real time

Unbalanced photosynthesis Photo Synthesis High energy compounds bright light produces lots of energy low-capacity biochemical pathways use it slowly Real time Potential for destruction.