1. PHOTOSYNTHESIS CH 10

2. Autotrophs are the worlds producers. Photoautotrophs produce organic molecules using solar energy. Chemoautotrophs produce organic molecules using energy from inorganic hydrogen sulfide or methane Plants, algae, cyanobacteria, phytoplankton are photoautotrophs Certain bacteria are chemiautotrophs

3. I. Overview of Photosynthesis Synthesis of glucose using sun’s NRG Is anabolic (endergonic) Occurs in photoautotrophs Occurs in 2 stages: – The light dependent reaction (LDR) uses the energy from the sun to make ATP and NADPH – The Calvin cycle uses the ATP and NADPH from the LDR to make a precursor to glucose The chemical reaction is: 6CO 2 + 6H 2 O + light → C 6 H 12 O 6 + 6O 2

4. II. The chloroplast: site of photosynthesis in eukaryotic cells structurally similar to photosynthetic prokaryotes and most likely evolved from them The light reactions take place in the membranes of the thylakoids The Calvin cycle takes place in the stroma

6. III. Photosynthesis and Aerobic Respiration: a series of redox reactions Transfer of electrons from reactant to product

7. in photosynthesis, water becomes oxidized and CO2 becomes reduced in photosynthesis, water is split using its electrons to reduce CO2

8. IV. The Two Stages of Photosynthesis: a preview

9. photosynthesis consists of 2 stages: – Light reactions (LDR) Split water Generate O2 Reduce NADP+ to NADPH Make ATP from ADP – Calvin Cycle Makes sugar from CO2 Uses ATP and NADPH

10. III. The Light Reactions (LDR): convert solar energy to the chemical energy of ATP and NADPH A. Light composed of different wavelengths also behaves like it has particles called photons

11. B. Photosynthetic Pigments pigments absorb wavelengths of visible light wavelengths not absorbed are reflected or transmitted why do plants appear green?

13. what wavelengths are used for photosynthesis? What pigments do these correspond to?

14. Chlorophylls absorb the photons of energy from RO IV Chlorophylls found in plants, algae, and cyanobacteria Cyanobacteria are ancestor of chloroplasts Other photosynthesizing bacteria have bacteriorhodopsin which absorbs green wavelengths

16. C. The components of the Light Reactions 1. Photosystem I and II They have: Light absorbing complex: contains chlorophyll and absorbs photons Reaction center: uses energy from photons to boost electrons.

17. 2. Electron Transport Chain (ETC) – series of proteins that transfer electrons by redox reactions 3. Proton pump – uses the energy in the electron to pump protons (H+) across the membrane. 4. NADP reductase – uses the energy from the boosted electron to make NADPH 5. ATP synthase – uses energy from the proton gradient to make ATP

18. D. How the light dependent reaction works Linear electron flow:

19. 1. photon strikes pigment of PSII and energy is transferred to P680 of chlorophyll and electron is boosted. P680 becomes oxidized 2. electron is transferred to electron acceptor 3. water is split and electron from water reduces oxidized P680 back to its original state. H+ ions enter thylakoid and oxygen is made 4. excited electron moves thru electron transport chain by redox reactions pumping H+ ions up the gradient 5. proton diffuse thru ATP synthase making ATP 6. photon strikes pigments of PS1 and energy is transferred to P700 and electron is boosted oxidizing P700. Electron boosted from P680 is used to reduce P700 7. excited electron from P700 moves thru electron transport chain by redox reactions 8. NADP reductase uses P700’s electrons to make NADPH

21. Chemiosmosis: http://faculty.nl.edu/jste/noncyclic_photoph osphorylation.htm http://highered.mcgraw- hill.com/sites/0072437316/student_view0/

22. Cyclic electron flow: Difference between cyclic and linear?

23. IV. The Calvin Cycle uses chemical energy of ATP and NADPH to reduce CO2 to sugar

24. It uses ATP and NADPH from the LDR as well as CO2 from the atmosphere to make a precursor to glucose (PGAL) It occurs in the stroma of the chloroplast RUBISCO is the enzyme that fixes CO2 to start the Calvin cycle http://glencoe.mcgraw- hill.com/sites/9834092339/student_view0/c hapter39/calvin_cycle.html http://glencoe.mcgraw- hill.com/sites/9834092339/student_view0/c hapter39/calvin_cycle.html

25. V. Alternative Methods of Carbon Fixation Most plants are C3 plants and use RUBISCO to fix CO2 into a C3 compound

26. A. Photorespiration When Rubisco uses O2 instead of CO2 Causes calvin cycle to shut occurs in C3 plants

27. C4 plants: CO2 is fixed by another enzyme, that can work with low CO2 levels C4 compound gives CO2 to RUBISCO CAM plants It is primarily the C4 pathway, but plants keep their stomata open at night when the atmospheric O2 levels decrease http://www.uic.edu/classes/bios/bios100/lec tures/c4.htm

28. V. How the LDR and Calvin cycle interact

29. How would adding an inhibitor to Calvin cycle affect photosynthesis? How would adding an inhibitor to ATP synthase affect photosynthesis?