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PHOTOSYNTHESIS

PHOTOSYNTHESIS. Photosynthesis. Converts sunlight energy into chemical energy. Chemical Equation. 6CO 2 + 6H 2 O + light energy C 6 H 12 O 6 + 6O 2 Carbon dioxide and water are the reactants and glucose and oxygen are the products.

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PHOTOSYNTHESIS

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  1. PHOTOSYNTHESIS

  2. Photosynthesis • Converts sunlight energy into chemical energy

  3. Chemical Equation • 6CO2+ 6H2O +light energyC6 H 12 O 6 + 6O2 • Carbon dioxide and water are the reactants and glucose and oxygen are the products. • Chlorophyll is the pigment necessary to run the reaction.

  4. Requirements • Light Energy (Sun) • Chlorophyll a,b and accessory pigments (these absorb wavelengths of light) • Raw materials (CO2 and H2O ) • Enzyme: NADP (taxi cab)

  5. Leaf has many layers of specialized cells. Notice the location of the chloroplasts. Cross Section of a Leaf

  6. Stomata • Stomata(leaf mouth) allows gas exchange (O2 and CO2) guard cells create the stomata

  7. Inside the Chloroplast • Saclike membranes called thylakoids contain chlorophyll and accessory pigments. • Stacks of Thylakoids are called Grana. • Stroma is the fluid filled space.

  8. Chloroplast Again Notice the grana are stacks of thylakoids • Chloroplast Below

  9. The Two Phases of Photosynthesis • Phase I - Light Dependent Reaction (occurs in thylakoids) • Light energy is absorbed and converted to chemical energy in the form of ATP and NADPH. • Phase II- Dark Reaction (Calvin Cycle) (occurs in stroma) • NADPH and ATP that were formed during light dependent reactions are used to make glucose.

  10. Light Reactions Overview: 1. Light energy is absorbed in the THYLAKOID. 2. Water is split or pulled apart: 2H and ½ O2 3. CO2 is NOTinvolved yet. 4. ATP is formed. 5. Reactants: chlorophyll, light energy, water, and NADP.

  11. Light Reactions Steps: • Light energy is absorbed by chlorophyll. • Electrons in chlorophyll become “excited” (high energy) and split H2O apart. H2O: 2H + ½ O2 * 6 molecules of water total are split apart: 12 H+ , 6, ½ O2(released into air as a byproduct). 3.An electron is released into the electron transport system.

  12. Light Reactions 4. NADP picks up the H + and electronsand transports them across the thylakoid membrane into the stroma. NADP + H +  NADPH * 6 H2O are split: 12 NADPH are formed by the Light Reaction.

  13. 5. Hydrogen protons (H+) move across the thylakoid into the stroma to create ATPs from ADPs.

  14. Products of Light Reactions • 6, ½ O2 are released into the air via stomata. • NADPH and ATPgo to the stroma for Phase II (The Calvin Cycle).

  15. Calvin Cycle or Dark Reaction • Reactants: • ATP and NADPH from Light Reactions • 6 CO2 • 6 RuBP (ribulosebisphosphates) • Products: Glucose (C6H12O6) and 6 RuBP • Takes place in the stroma.

  16. Steps of the Calvin Cycle (Dark Reaction) • CO2 Fixation: CO2 combines with RuBP6CO2 + 6RuBP 12 PGA PGA is a 3-Carbon molecule and is UNSTABLE! Total: 6 CO2 + 6 RuBP 12 PGA

  17. Calvin Cycle 12 PGA + 12 ATP + 12 NADPH 12 G3P+ 12 ADP + 12 NADP * What happens to NADP? ADP? * PGA and PGAL are 3 Carbon molecules.

  18. Calvin Cycle Con’t. • Formation of glucose: 2G3P 2Glucose C3H6O3 + C3H6O3  C6H12O6 * Recall: G3Pis a 3- Carbon molecule.

  19. Calvin Cycle

  20. Importance of Photosynthesis • Forms glucose which is necessary for cellular respiration. • Forms the source of oxygen we breathe.

  21. Factors that Affect Photosynthesis • 1. Amount of water • 2. Temperatures • 3. Light Intensity • 4. Amount of CO2

  22. Summary of Photosynthesis

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