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Photosynthesis

Photosynthesis. Bio 391 – Ch4 How Exactly is Sunlight captured and converted into Food?. Light Reaction http://vcell.ndsu.edu/animations/photosynthesis/movie.htm. Calvin-Benson Cycle http://www.youtube.com/watch?v=mHU27qYJNU0. What are autotrophs?. Obtains energy from nonliving sources

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Photosynthesis

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  1. Photosynthesis Bio 391 – Ch4 How Exactly is Sunlight captured and converted into Food?

  2. Light Reactionhttp://vcell.ndsu.edu/animations/photosynthesis/movie.htm Calvin-Benson Cycle http://www.youtube.com/watch?v=mHU27qYJNU0

  3. What are autotrophs? • Obtains energy from nonliving sources • Photoautotrophs • Photosynthesis • Sun energy converts CO2 into sugars • Enzymes convert sugars into amino acids and other needed compounds • Chemoautotrophs • Specialized bacteria • No sunlight – use energy of inorganic substances (Fe, S, etc.)

  4. Review Question #1 • the energy of radio waves. • sulfur and other inorganic materials . • an inexhaustible energy source. • fungi, bacteria, and other one-celled organisms. Photoautotrophs have adapted to take advantage of…

  5. Nature of Light • Rays • Photons • Waves • Electricity Light is a form of electromagnetic radiation. How does it travel?

  6. Waves • Crest • Trough • Peak • Frequency What is the highest point of a wave called?

  7. Waves 2 • Frequency • Wavelength • Waveheight • Amplitude What is the distance between two waves called?

  8. Electromagnetic Spectrum • Wide range of energy types • λ = wavelength • Visible Light • ROYGBIV • Excites pigment molecules which trap energy

  9. Wavelength & Energy • The higher wavelengths have lower energy. • The higher wavelengths have higher energy. • The lower wavelengths have lower energy. • There is no connection between wavelength and energy. What is the connection between wavelength and energy of the waves?

  10. Wavelength & Energy 2 Which color light has the highest wavelength and lowest energy? • Red • Violet • Green • Blue

  11. Electromagnetic Radiation

  12. Chloroplasts • Structure • Thylakoids & pigment • Granum • Stroma • Own DNA & RNA

  13. Video 3 Video 3 • Click the image to play the video segment. Light-Dependent Reactions, Part 1

  14. Chlorophyll • In the violet/blue and orange/red range. • In the black/white and orange/yellow range. • Of all visible wavelengths. • Primarily in the green range. Chlorophyll absorbs light …

  15. Chlorophyll & Accessory Pigments • Two types – “a” and “b” • Absorbs violet-blue and orange-red colors • ~ 350-500 nm & 650-700 nm • Reflects green  plants have green color • Accessory Pigments • Absorb other colors of light and transfer Σ to chlorophyll-a • Most noticeable in the fall months • EX: carotenoids

  16. Simplified Photosynthesis • Light Reactions • Pigments in thylakoids absorb light • Light converted into chemical Σ • Calvin Cycle (a.k.a. “Dark Reactions”) • Chemical Σ used to make 3 carbon sugars from CO2 • Used to make more complex sugars or other biochemical molecules • Overall Reaction • 3CO2 + 3H2O  C3H6O3 + 3O2 • 6CO2 + 6H2O C6H12O6 + 6O2

  17. Video 4 Video 4 • Click the image to play the video segment. Light-Dependent Reactions, Part 2

  18. Light Reactions • Electrons to flow from water to NADP+ • Hydrogen and oxygen bond to produce water • Sulfur particles to bond to water molecules • Electrons to diffuse across the Calvin membrane In the chloroplast, light energy causes…

  19. Light Reaction Products • H2O, CO2, ATP • O2, NADPH, ATP • NADPH, H2O, ADP • O2, ATP, CO2 The products of the light reactions are…

  20. Review #3 During photosynthesis what happens to the oxygen atoms in water molecules? • They help form carbohydrates • They act as hydrogen-acceptor molecules • They end up as oxygen gas • They help form both carbohydrates and water.

  21. LIGHT REACTION

  22. Review : What just happened? Make a list of steps from sun to ATP 2. Summarize the main points

  23. Cyclic v. Noncyclic Photophosphorylation • http://highered.mcgraw-hill.com/olc/dl/120072/bio12.swf • Talking textbook • Simple vs. Complex Autotrophs • Generates ATP but not NADPH. Why?

  24. Calvin Cycle Summary RuBP unstable 6C sugar (5C) CO2 PGA PGA (3C) (3C) ATP ATP 5 PGAL to regenerate PGAL (3C) NADPH NADPH 1 PGAL released for growth PGAL (3C) 6 PGAL 3x

  25. Video 5 Video 5 • Click the image to play the video segment. Calvin Cycle

  26. Calvin Cycle • Keys to understanding…. • It’s all about rearrangement • 6 (1) + 6(5) = 12 (x) • What makes that statement true? • 6 (CO2) + 6 (RuBP) = 12(PGA) • 10 (3) = 6 (x) • 10 (PGA) = 6 (RuBP)

  27. Calvin Cycle Summary • Each turn fixes 1C • 3 turns = 1 PGAL • PGAL is a carbon skeleton • Lipids • Amino acids  proteins • Glucose, sucrose, starch • Rubisco • Catalyzes CO2 fixation • Activated by light thus Calvin cycle requires some level of light to occur • “C3 plants” – those that fix CO2 into 3C PGAL

  28. Concept Map Section 8-3 Photosynthesis includes takes place in uses use take place in to produce to produce of

  29. Light- dependent reactions Calvin cycle Energy from sunlight Thylakoid membranes ATP Stroma NADPH High-energy sugars ATP NADPH O2 Chloroplasts Concept Map Section 8-3 Photosynthesis includes takes place in uses use take place in to produce to produce of

  30. Factors Effecting the Rate of Photosynthesis Sections 4.5 – 4.6

  31. More light = higher rate Reaches saturation point Enzymes of light reaction going as fast as possible Higher than saturation point  PS declines Chlorophyll accumulates light faster than it can transfer it to ETS Extra energy goes to oxygen producing OH- when reaction w/H2O OH- or H2O2 damages chloroplasts Light Intensity PHOTOINHIBITION

  32. Similar to light intensity Hits a saturation point Does not decline after saturation CO2 Concentration

  33. Optimal temperature range If too high… Proteins denature If too low… Molecular movement is slower High Temps = Stomata close Prevents water loss Increases photorespiration C4 and CAM adaptations Temperature

  34. O2 Concentration • Rubisco binds CO2 and O2 equally as well • Molecular shapes are similar • Halves productivity of PGA production • Gycolate broken down to CO2 • Benefits? • Occurs when stomates close • Evolutionary Adaptations: • C4 and CAM plants

  35. Leaf Anatomy

  36. C4 Plants:Reducing Photorespiration • 2 cell types: • Mesophyll & bundle sheath • No rubisco in mesophyll cells • 2 fixation enzymes • RuBP carboxylase • PEP carboxylase • Fix CO2 as 4-C acid • Then fix it again as 3-C

  37. Reducing Photorespriation:CAM plants • Crassulacean acid metabolism • Open stomates at night, close during the day • CO2 + 3C  4C saved until morning • 4C  3C + CO2  Calvin Benson cycle • Grow very slowly

  38. 1. Which graph represents an increasing light intensity before saturation?2. Which light intensity graph represents photorespiration if the x axis is relabeled as oxygen?3. Which unlabeled graph represents increasing CO2 on the x axis?

  39. Releases O2 Stores energy Releases CO2 Uses CO2 Releases energy Produces sugar Uses sugar Uses O2 Photosynthesis Cell respiration Both Neither Match Outcomes (Left) with Process (Right)

  40. Releases O2 Stores energy Releases CO2 Uses CO2 Releases energy Produces sugar Uses sugar Uses O2 Plants Animals Both Neither Match Outcomes (Left) with Organisms (Right)

  41. Rainbows are separated white light

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