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LB145 F11 Thursday September 29, 2011 Class Outline

LB145 F11 Thursday September 29, 2011 Class Outline. Photosynthesis A Carrot (Eyes on the Prize) Capturing Light Using Light Energy to Do Work!. Evidence Supporting Endosymbiont Origin of Mitochondria and Chloroplasts. Chloroplast ribosomes are very similar to eubacterial ribosomes

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LB145 F11 Thursday September 29, 2011 Class Outline

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  1. LB145 F11Thursday September 29, 2011 Class Outline • Photosynthesis • A Carrot (Eyes on the Prize) • Capturing Light • Using Light Energy to Do Work!

  2. Evidence Supporting Endosymbiont Origin of Mitochondria and Chloroplasts • Chloroplast ribosomes are very similar to eubacterialribosomes • Chloroplast DNA sequences come out with bacterial DNA sequences in molecular phylogenies

  3. Cytoplasm Plasma membrane DNA Ancestral prokaryote Model for Serial Endosymbiosis and the Origin of Eukaryotes Endoplasmic reticulum Nucleus Nuclear envelope Aerobic heterotrophic prokaryote Photosynthetic prokaryote Mitochondrion Mitochondrion Ancestral heterotrophic eukaryote Plastid Ancestral photosynthetic eukaryote Campbell 8e, Fig. 25.9

  4. Photosynthesis – Minute Paper(worth 1 point) • What is the relationship of the light and dark reactions of photosynthesis? In other words, what things are produced in each set of reactions, and how does one set of reactions depend on the other?

  5. Photosynthesis – Connect the two halves!!! CO2 H2O Light NADP+ ADP + P i Calvin Cycle Light Reactions ATP NADPH Chloroplast [CH2O] (sugar) O2 Campbell 8e, Fig. 10-5-4

  6. Photosynthesis – Minute Paper (Pt. 2)(worth1 more point) • What is the relationship of the light and dark reactions of photosynthesis? In other words, what things are produced in each set of reactions, and how does one set of reactions depend on the other? • How does a root cell, in a photosynthetic plant like a carrot, obtain food? How do these root cells use this food?

  7. Photosynthesis • How does a cell at the growing point of a plant root get the energy it needs to grow and divide?

  8. Change the scale of your thinking! Organelle-level

  9. Photosynthetic Leaf Section Organ-level Guard cells Key to labels Stomatal pore 50 µm Dermal Epidermal cell Ground Cuticle Sclerenchyma fibers Vascular Campbell 8e, Fig. 35-18 Stoma (b) Surface view of a spiderwort (Tradescantia) leaf (LM) Upper epidermis Palisade mesophyll Spongy mesophyll Bundle- sheath cell Lower epidermis 100 µm Cuticle Xylem Vein Phloem Vein Air spaces Guard cells Guard cells (a) Cutaway drawing of leaf tissues (c) Cross section of a lilac (Syringa)) leaf (LM)

  10. Plants make sugar in their leaves • How does a cell at the growing point of a plant root get the energy it needs to grow and divide?

  11. Vascular Bundles • Phloem - All plant tissues need sugars made in photosynthetic tissue • Xylem - Stems and leaves need water and minerals from the roots

  12. Sucrose from the leaves is shipped to the roots! • Phloem - sugar transport • There is phloem in the leaves • There is phloem in the stems • There is phloem in the roots

  13. Think about the plant as a whole organism! • Where does it get made? • Where does it get used? • How does it get there?

  14. Source cell(leaf) Vessel(xylem) Sieve tube(phloem) Loading of sugar 1 Sucrose Transport(in plant vascular tissue) H2O Sucrose 1 H2O 2 Fig. 36-20 Uptake of water 2 Bulk flow by positive pressure Bulk flow by negative pressure Unloading of sugar 3 Sink cell(storageroot) Water recycled 4 3 4 Sucrose H2O

  15. Sieve-tube elements: longitudinal view (LM) 3 µm Sieve Tubes Sieve plate Sieve-tube element (left) and companion cell: cross section (TEM) Companion cells Fig. 35-10e Sieve-tube elements Plasmodesma Sieve plate 30 µm 10 µm Nucleus of companion cells Sieve-tube elements: longitudinal view Sieve plate with pores (SEM)

  16. Sucrose Loading(there’s your co-transporter, in action!) Fig. 36-19 High H+ concentration Cotransporter Mesophyll cell Protonpump H+ Companion(transfer) cell Sieve-tubeelement Cell walls (apoplast) S Plasma membrane Plasmodesmata Key ATP Sucrose Apoplast H+ H+ S Bundle-sheath cell Phloemparenchyma cell Low H+ concentration Symplast Mesophyll cell

  17. Why sucrose?

  18. Why sucrose? • ATP is a lousy transport form of energy!

  19. Why sucrose? • ATP is a lousy transport form of energy! • ATP is a lousy storage form of energy!

  20. Chloroplasts are not the only plastids!

  21. How did Engelmann figure this out? Campbell 8e, Fig. 10.9

  22. Photosynthetic Pigments

  23. Photosynthetic Antennal Complex Photosynthetic pigments are arranged in an array

  24. Change the scale of your thinking! Organelle-level

  25. Chlorophyll molecules transmit energy from excited electrons in the antenna complex to a reaction center

  26. Photosystem Football • Antennal Complex – C106 chairs and tables • Reaction Center – Front Row Team • Primary Electron Acceptor – Help me out! • A Photon of Light – The Football

  27. Photosynthesis Movie http://35.9.122.184/Photosynthesis.mov

  28. PHOTOSYSTEM II (Feb 2004) Photosynthesis uses light energy to drive the oxidation of waterat an oxygen-evolving catalytic site within photosystem II (PSII).We report the structure of PSII of the cyanobacteriumThermosynechococcuselongatus at 3.5 Å resolution. We have assigned most ofthe amino acid residues of this 650 kDadimericmultisubunitcomplex and refined the structure to reveal its molecular architecture.Consequently we are able to describe details of the bindingsites for cofactors and propose a structure of the oxygen-evolvingcenter (OEC). The data strongly suggest that the OEC containsa cubane-like Mn3CaO4 cluster linked to a fourth Mn by a mono-µ-oxobridge. The details of the surrounding coordination sphere ofthe metal cluster and the implications for a possible oxygen-evolvingmechanism are discussed. Kristina N. Ferreira, Tina M. Iverson, KarimMaghlaoui, James Barber, and So Iwata (2004) Architecture of the Photosynthetic Oxygen-Evolving Center Science [DOI: 10.1126/science.1093087]

  29. The Z-Scheme What is the error (or forced misconception) in this diagram?

  30. Photosynthesis Movie http://35.9.122.184/Photosynthesis.mov

  31. The Z-Scheme What is the error (or forced misconception) in this diagram?

  32. The Z-Scheme What is the error (or forced misconception) in this diagram?

  33. Campbell 8e, Fig. 10-17 Chloroplast Electron Transport Chain – DOES NOT Yield ATP Directly!!! STROMA (low H+ concentration) Cytochrome complex Photosystem I Photosystem II Light 4 H+ NADP+ reductase Light 3 Fd NADP+ + H+ NADPH Pq Pc e– 2 e– H2O O2 1/2 1 THYLAKOID SPACE (high H+ concentration) 4 H+ +2 H+ To Calvin Cycle Thylakoid membrane ATP synthase STROMA (low H+ concentration) ADP + ATP P i H+

  34. Chloroplast Electron Transport Chain: Where does ATP synthesis take place (and why)? STROMA (low H+ concentration) Cytochrome complex Photosystem I Photosystem II Light Campbell 8e, Fig. 10-17 4 H+ NADP+ reductase Light 3 Fd NADP+ + H+ NADPH Pq Pc e– 2 e– H2O O2 1/2 1 THYLAKOID SPACE (high H+ concentration) 4 H+ +2 H+ To Calvin Cycle Thylakoid membrane ATP synthase STROMA (low H+ concentration) ADP + ATP P i H+

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