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Photosynthesis

Photosynthesis. Energy & Life. Photosynthesis. Plants use the Energy of sunlight to convert Water (H 2 0) and Carbon Dioxide (CO 2 ) into Oxygen (O 2 ) and High Energy Carbohydrates (sugars, e.g. Glucose) & Starches. The Photosynthesis Equation. [ Waste product ]. Glucose.

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Photosynthesis

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  1. Photosynthesis Energy & Life

  2. Photosynthesis • Plants use the Energy of sunlight to convert Water (H20) and Carbon Dioxide (CO2) into Oxygen (O2) and High Energy Carbohydrates (sugars, e.g. Glucose) & Starches

  3. The Photosynthesis Equation [Waste product]

  4. Glucose • Glucose is a monosaccharide • C6H12O6 • One Molecule of glucose Stores 90 Times More Chemical Energy Than One Molecule of ATP

  5. History of Photosynthesis

  6. Early Questions on Plants Several Centuries Ago, The Question Was:Does the increase in plant mass come from the air? The soil? The water?

  7. Van Helmont’sExperiment1643 • Planted a seedling into A pre-measured amount of soil and watered for 5 years. • Weighed Plant & Soil. Plant- gained 75 kg, Soil- same weight. • Concluded increase in Mass Came From Water

  8. Priestley’s Experiment 1771 • Burnedcandle in Bell Jar until it went out. • If placed sprig of Mint in Bell Jar for afew days, candle could be relit and burn. • Concluded plants released substance (O2)necessary for burning.

  9. Ingenhousz’sExperiment1779 Repeated Priestly experiment with & without sunlight

  10. Results of Ingenhousz’sExperiment • Showed that Priestley’s results only occurred in the presence of Sunlight. • Light was necessary for plants to produce the “burning gas” or oxygen

  11. Julius Robert Mayer 1845 Proposed that plants can convert Light Energy intoChemical Energy

  12. Samuel Ruben & Martin Kamen 1941 Used Isotopes to determine that the Oxygenliberated[released] in Photosynthesis comes from water RUBIN KAMEN

  13. Melvin Calvin 1948 • First to trace the path that carbon (CO2) takes in forming Glucose • Does NOT require sunlight • Called the Calvin Cycle or Light Independent Reaction • Also knownas the Dark Reaction

  14. Autotrophs Organisms that contain chlorophyll and are able to use light energy from the sun to produce their own food. Plant Euglena

  15. Heterotrophs • Heterotrophs are organisms that can NOT make their own food • Heterotrophs can NOT directly use the sun’s energy

  16. Importance of ATP Principal Compound Used To Store Energy In Living Organisms

  17. Cells Using Biochemical Energy Cells Use ATP For: • Active transport • Movement • Photosynthesis • Protein Synthesis • Cellular respiration • All other cellular reactions EVERYTHING!

  18. ATP – Cellular Energy • Adenosine Triphosphate • Contains two, high-energy phosphate bonds • Also contains the nitrogen base adenine & a ribose sugar

  19. Sugar in ADP & ATP • Called ribose • Pentose sugar • Also found in RNA

  20. Releasing Energy From ATP • ATP provides all of the energy for cell activities • The high energy phosphate bonds are BROKEN to release energy • ATP is constantly being used and remade by cells • The process of releasing ATP’s energy & reforming the molecule is called phosphorylation

  21. Phosphorylation Enzyme in thylakoid membrane called ATP Synthase As H+ ions passed through thylakoid membrane, enzyme binds them to ADP Forms ATP for cellular

  22. Releasing Energy From ATP • Adding A Phosphate Group To ADP stores Energy in ATP • Removing A Phosphate Group From ATP Releases Energy & forms ADP. Loose Gain

  23. More on ATP • Cells Have Enough ATP To Last For A Few Seconds • ATP must constantly be made • ATP Transfers Energy Very Well • ATP Is NOT Good At Energy Storage

  24. Plant Pigments & Cell Structure

  25. Light and Pigments Longest wavelength • Energy From The Sun Enters Earth’s Biosphere As Photons, a light energy unit. • Visible or ‘White’ Light contains amixture Of different wavelengths • Different wavelengths are seen as Different Colors Shortest wavelength

  26. Pigments • In addition to water, carbon dioxide, and light energy, photosynthesis requires Pigments • Chlorophyll is the primary light-absorbing pigment in autotrophs • Chlorophyll is found inside chloroplasts

  27. Chlorophyll There are 2 main types of chlorophyll molecules: Chlorophyll a Chlorophyll b A third type, chlorophyll c, is found in dinoflagellates

  28. Light wavelength absorbed by pigments Chlorophyll a absorbs Blue = best Red = 2nd best Chlorophyll reflects green

  29. Chlorophyll • Absorbs blue wavelength best and red wavelength 2nd best. • Does NOT absorb green wavelength, but reflects green wavelength. • This is why plants look green.

  30. Carotenoids • Plant pigment • Absorbs light energy best in the yellow, orange and red wavelengths. • Chlorophyll masks these pigments

  31. Color Note • pigments that absorb all wavelengths of light are black. • pigments that reflect all wavelengths of light are white.

  32. Chlorophyll a • Found in all plants, algae, & cyanobacteria • Makes photosynthesis possible • Participates directly in the Light Reactions • Can accept energy from chlorophyll b

  33. Chlorophyll b • Chlorophyll b is an accessory pigment • Chlorophyll b acts indirectly in photosynthesis by transferring the light it absorbs to chlorophyll a • Like chlorophyll a, it absorbs red & blue light and REFLECTS GREEN

  34. Leaf Structures • Cuticle- Waxy outer layer • Epidermal Cells – Waxy and rigid outer cell layer. • Stomata - Openings in the epidermis that allow gas and water exchange. • Mesophyll layer- spongy layer of cells within leaf where photosynthesis takes place.

  35. Leaf Structure

  36. Structure of the Chloroplast • Double membrane organelle • Thylakoids – flattened sac that contains photosynthesis pigments. Where light dependent reactions occur. • Granun (grana-plural) Stack of connected Thylakoid sacks. • Stroma- Gel-like material around grana.

  37. Inside A Chloroplast

  38. Light & Pigments • Pigmentsabsorb different wavelengths of light which “excite” electrons in the plant’s pigments. • Excited electrons carry the absorbed energy • Electrons are transported by an electron carrier called NADP+

  39. Light Dependent Reactions • Occurs across the thylakoid membranes • Uses light energy • Produce Oxygen from water • Convert ADP to ATP • Also convert NADP+ into the energy carrier NADPH

  40. Energy Carrier • NADP+ =Nicotinamide adenine dinucleotide phosphate • Accepts 2 high energy electrons and a H+ from the Light Reaction which convert NADP+ into NADPH. • High energy electrons used to build molecules cell needs like glucose.

  41. NADPH

  42. Light Dependent Reaction

  43. Light Reaction Summary Reactants: • H2O • Light Energy Products: • Oxygen Energy to drive Dark Reaction • ATP • NADPH

  44. Function of the Stroma • Light Independent reactions occur here • ATP used to make carbohydrates like glucose • Location of the Calvin Cycle

  45. Light Independent Reaction • Also known as the Calvin Cycle OR Dark Reaction. • Does not require light. • Occurs in thestroma • Uses ATP and NADPH from the light-dependent reactions to produce high-energy sugars.

  46. Light Independent Reaction • Uses: ATP & NADPH from light reactions used as energy source • 6 Atmospheric C02 are used to make sugars like glucose and fructose • Six-carbon Sugars made during the Calvin Cycle

  47. The Calvin Cycle

  48. Light Independent Reaction Summary Reactants: • CO2 • Energy from ATP & NADPH Products: • ADP • NADP+ • Sugars

  49. Factors Affecting the Rate of Photosynthesis • Amount of available water • Temperature • Amount of available light energy

  50. Photosynthesis Overview

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