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Photosynthesis; Using Light to Make Food

Photosynthesis; Using Light to Make Food. What is Photosynthesis?. Process plants use to make their own food Photosynthesis is how plants (and some bacteria) use the energy of the sunlight to convert water and carbon dioxide into oxygen and high-energy carbohydrates.

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Photosynthesis; Using Light to Make Food

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  1. Photosynthesis; Using Light to Make Food

  2. What is Photosynthesis? • Process plants use to make their own food • Photosynthesis is how plants (and some bacteria) use the energy of the sunlight to convert water and carbon dioxide into oxygen and high-energy carbohydrates. • Plants’ leaves contain chlorophyll • Chlorophyll is the pigment that(green color) makes photosynthesis possible

  3. Photosynthesis • What are the two parts? • A. Light Reaction • B. Dark Reaction • Where does each occur? • A. Thylakoid • B. Stroma

  4. Photosynthetic Equation sunlight → chlorophyll • 6CO2 + 6H2O C6H12O6 + 6O2 Carbon Dioxide + Water Sugar + Oxygen Plants have pigments that allow them to take in certain wavelengths of light. Chloroplasts hold chlorophyll, a pigment that takes in light, that can be turned into energy. There is one color of light that plants do not take in very well, green.

  5. Site of Photosynthesis in Leaves

  6. Chloroplast Structure

  7. Scientists & Their Contributions • Jean Baptiste van Helmont - determined that the mass of the plant did not come from the soil. He conducted an experiment using a seedling and watched it grow for 5 years. He only watered it. It weighed 75 kg. He thought that water only contributed to the mass which was incorrect.

  8. Scientists & Their Contributions • Joseph Priestley– determined that oxygen was produced by the plant. He conducted an experiment using a candle and a mint sprig. He put a candle under a dome and after a certain time, the candle went out. The mint sprig produced a substance which allowed the candle to stay lit longer. He also conducted this experiment using mice and the mint sprig.

  9. Scientists & Their Contributions • Jan Ingenhousz – repeated Priestley’s experiment and showed that light was required for the plant to produce oxygen.

  10. The chlorophyll absorbs the sunlight.

  11. The sunlight is combined with water, Carbon Dioxide and nutrients from the soil. CO2

  12. The chlorophyll processes the ingredients and makes sugar(plant food, glucose) and oxygen. Glucose + Oxygen O2

  13. Photosynthesis in Chloroplasts Chloroplast Chloroplast NADP+ ADP + P Light- Dependent Reactions Calvin Cycle ATP NADPH

  14. Light Reactions

  15. Steps of the Light Reaction • Light Absorption • ETC (Electron Transport Chain) • Oxygen Production (From the splitting of water) • ATP and NADPH Formation • The wavelength of PSI is 700 nm • The wavelength of PSII is 680 nm

  16. Light Reaction • Occurs in the thylakoid membrane or granum Description of Step #1 • Electrons get excited, leave the chlorophyll molecules and travel to an electron acceptor

  17. Description of Step #2Electron Transport Chain (ETC) • Electrons are transported through the ETC by electron carriers • Electrons lose energy as they travel down the ETC • Electrons travel to PSI (P700) and are re-energized • Then they travel to another electron carrier, down a 2nd ETC

  18. Water Splits Description for Step #3 • Hydrogen electrons replace the ones that left PSII • Oxygen goes into the atmosphere Description for Step #4 ATP and NADPH Formation • Hydrogen atoms create a difference in charges across the thylakoid membrane allowing a phosphate group to bind with ADP creating ATP • Hydrogen combines with NADP+ to make NADPH

  19. Products of the Light Reaction • Oxygen • ATP • NADPH

  20. Light Dependent Reaction

  21. Calvin Cycle CO2 Enters the Cycle Energy Input 5-Carbon Molecules Regenerated ChloropIast 6-Carbon Sugar Produced

  22. Steps of the Dark Reaction • Also called the Calvin Cycle and the Light Independent Reaction • Occurs in the stroma Description of Step#1 • RuBP (ribulosebisphosphate) + CO2 (carbon dioxide) yields PGA (phosphoglyceric acid); carbon fixation

  23. Description of Step #2 • PGA (phosphoglycerate or phosphoglyceric acid) is converted into PGAL (phosphoglyceraldehyde) using NADPH and ATP; energy consumption and redox reaction (oxidation/reduction reaction) Description of Step #3 • PGAL leaves the cycle Description of Step #4 • PGAL is converted back into RUBP; regeneration of RUBP • The importance is to produce glucose • Six turns of the cycle yields one glucose molecule

  24. Light- dependent reactions Calvin cycle Energy from sunlight Thylakoid membranes ATP Stroma NADPH High-energy sugars ATP NADPH O2 Chloroplasts Summary of Photosynthesis Photosynthesis includes takes place in uses use take place in to produce to produce of

  25. Plants and animals need each other to survive.

  26. Animals including humans make and exhale the CO2 (carbon dioxide) plants need.They (the plants) make the O2 (oxygen) and food we need.

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