1 / 30

PHOTOSYNTHESIS SBI4U

PHOTOSYNTHESIS SBI4U. Diana Puia. CURRICULUM EXPECTATIONS. C3.2 explain the chemical changes and energy conversions associated with the process of photosynthesis (e.g., carbon dioxide and water react with sunlight to produce oxygen and glucose)

elmo-wyatt
Download Presentation

PHOTOSYNTHESIS SBI4U

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. PHOTOSYNTHESISSBI4U Diana Puia

  2. CURRICULUM EXPECTATIONS C3.2 explain the chemical changes and energy conversions associated with the process of photosynthesis (e.g., carbon dioxide and water react with sunlight to produce oxygen and glucose) C3.3 use the laws of thermodynamics to explain energy transfer in the cell during the processes of cellular respiration and photosynthesis. C3.4 describe, compare, and illustrate (e.g., using flow charts) the matter and energy transformations that occur during the processes of cellular respiration (aerobic and anaerobic) and photosynthesis, including the roles of oxygen and organelles such as mitochondria and chloroplasts.

  3. AGENDA • Which organisms perform photosynthesis? • What is photosynthesis? (Overview) • Where does it happen? • Light as a source of energy • Light-dependent reactions • Photosystem I • Photosystem II • Calvin cycle

  4. Which Organisms perform Photosynthesis? PHOTOAUTOTROPHS • Plants (a) Sunflowers • Algae (b)Spirogyra • Protists (c)Euglena gracilis • Cyanobacteria (d) Anabaena NOTE: blue-green algae bacteria in oceans produce the most O2.

  5. What is Photosynthesis? The process which transforms light energy into chemical energy. OVERALLREACTION: light energy 6CO2 + 6H2O C6H12O6 + 6O2

  6. What is Photosynthesis? LIGHT-DEPENDENT REACTIONS (the photo part) • Requires H2O, chlorophyll, and light energy (from any light). • Produces O2, ATP, and NADPH CALVIN CYCLE (the synthesis part) • Requires ATP, NADPH, and CO2. • Produces glucose (sugars), ADP+Pi, and NADP+ light energy 6CO2 + 6H2O C6H12O6 + 6O2

  7. PhotosynthesisOverview

  8. Why is photosynthesis important? • Directly or indirectly, photosynthesis nourishes almost the entire living world: • Makes energy-rich organic molecules(glucose) from energy-poor inorganic molecules (CO2 and H2O) • It is the start of all food chains & webs. • It also makes oxygen.

  9. Where does photosynthesis happen? • Photosynthesis happens in: • Palisade layer • Spongy layer

  10. Chloroplasts ENDOSYMBIOTIC THEORY: • An ancestor of cyanobacteria was engulfed by an ancestor of today’s eukaryotic cells. • Symbiotic relationship – eukaryote offered protection, cyanobacteria offered food. • Chloroplasts are structurally similar to and likely evolved from photosynthetic bacteria.

  11. Structure of a chloroplast

  12. Light as a Source of Energy • 60% absorbed by the atmosphere • 40% reaches plants on Earth. • Only 5% of that is used in photosynthesis.

  13. What is light? • A form of electromagnetic (EM) radiation. • Travels in wave packs as photons (also known as quanta). • Photon wavelength is inversely proportional to energy(the shorter the wavelength, the “bluer” the light, the higher the energy).

  14. Engelmann video T.W. Engelmann’s Experiment (1882) • Used Spirogyra – has a long spiral chloroplast throughout its length. • Added aerobic bacteria to the slide. • Placed a triangular prism between the light source and the stage. • Found that bacteria accumulated where oxygen was produced the most (in areas exposed to red and blue-violet light).

  15. The Absorption Spectrum of Chlorophyll A and B

  16. Photosynthetic Pigments • Chlorophyll a (blue-green) • Chlorophyll b (yellow-green) • Carotenoids (yellow-orange) • Xanthophylls (yellow) • Anthocyanins (red, violet, blue)

  17. CHLOROPHYLL COMPOSED OF 2 PARTS: Porphyrin ring Hydrocarbon chain TWO COMMON TYPES: Chlorophyll a – methyl (CH3) Chlorophyll b – aldehyde (CHO)

  18. Coloured leaves? • Right: mosaic forest (same season) • Bottom: summer vs. autumn leaves

  19. Capturing light energy: photosystems PHOTOSYSTEMS CONSIST OF: • Antenna complex – captures light first • Reaction centre – chlorophyll a molecule

  20. Capturing light energy: photosystems Main photosynthetic pigment: • Chlorophyll a (two types: p680 and p700) Accessory pigments: • Chlorophyll b – broader spectrum used for photosynthesis. • Carotenoids – absorb excessive light that would damage chlorophyll.

  21. Photoexcitation What happens when a chlorophyll molecule interacts with light energy (photons)? • Before light strikes the molecule, electrons are at ground state. • Photon of light hits. • Electron excited to higher energy state. • Electron falls back down to ground state and gives off a photon of energy (flourescence) and some heat.

  22. Fluorescence DEMO ChlorophyllFluorescence • Isolated chlorophyll molecules fluoresce when separated from the photosynthetic membrane in which they are normally embedded. • If illuminated in bright white light, an isolated solution of chlorophyll will fluoresce, giving off red light and heat.

  23. Photosystems The two photosystems work together to start the process of photosynthesis Photosystem I (PSI) Photosystem II (PSII) Contains p680 chlorophyll a. Absorption peaks at 680nm red light. Found in the thylakoid membrane. Contains p700 chlorophyll a. Absorption peaks at 700nm red light. Found in the thylakoid membrane.

  24. Electron transport Non-cyclic (linear) electron flow and chemiosmosis

  25. Energy video Non-cyclic electron flow (Z-diagram) Pathways and energy changes are shown in a graph form.

  26. Cyclic electron flow A non-sustainable pathway.

  27. Melvin Calvin (1911-1997) • Determined the details of the cycle in the early 1960’s. • Received a Nobel prize in Chemistry in 1961.

  28. Calvin Cycle (dark light-independent reactions) The Calvin Cycle needs: • ATP (from the light reactions) • H atoms from NADPH (from the light reactions) • CO2(from the environment) 3 phases: • Carbon fixation • Reduction reactions • Regeneration of RuBP

  29. Calvin Cycle video

More Related